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Speaker 1: Get in touch with technology with tech Stuff from how

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Speaker 1: stuff Works dot com. Hey there, and welcome to tech Stuff.

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Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer with

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Speaker 1: how Stuff Works in I Love all Things Tech. And

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Speaker 1: in our last episode, I traced the history and evolution

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Speaker 1: of forensic science and how it kind of grew up

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Speaker 1: of out of a bunch of other kind of parallel

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Speaker 1: developing areas of investigation. And today we look at forensic

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Speaker 1: science as a collection of these various techniques and technologies

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Speaker 1: to to investigate crime and to solve crime. So today

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Speaker 1: I wanted to look more at some of the actual

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Speaker 1: tech use. I was kind of light on the tech

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Speaker 1: in the last episode. I was talking more about the

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Speaker 1: evolution of the ideas behind it, because that really informs

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Speaker 1: how the tech itself evolved. And today we're gonna look

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Speaker 1: a little more closely at that now. In the last episode,

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Speaker 1: I did mention the comparison microscope, that is a microscope

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Speaker 1: that is typically a pair of light microscopes. Isn't the

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Speaker 1: microscopes that use light as the medium to magnify stuff

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Speaker 1: into your eyeballs, So the companion or comparison microscope is

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Speaker 1: a pair of these right, it's it's essentially side by

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Speaker 1: side two light microscopes that are actually bridged together, but

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Speaker 1: on casual glance it looks almost like kind of binoculars

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Speaker 1: in a way. And here's a quick rundown on how

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Speaker 1: light microscopes work so that you can understand what a

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Speaker 1: comparison microscope is able to do. A basic upright light

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Speaker 1: microscope the kind you might see in a high school

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Speaker 1: lab or even you know, I guess elementary school and

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Speaker 1: middle school labs. Now when when I was a student,

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Speaker 1: they didn't let a play with us until we were

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Speaker 1: essentially high schoolers. But you are probably familiar what what

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Speaker 1: these look like. It's that little upright microscopees gun. I

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Speaker 1: piece at one end has a little platform it's called

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Speaker 1: the stage where you would put a sample to h

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Speaker 1: to examine. Well, they're called light microscopes because they have

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Speaker 1: a light source at the base. Typically, your basic upright

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Speaker 1: light microscope does that shines light up through a sample

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Speaker 1: so that you can see it when you're looking through

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Speaker 1: the I piece above. The light source is a special

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Speaker 1: lens called a condenser. Now, the condenser's purpose is to

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Speaker 1: redirect a divergent beam of light from a light source

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Speaker 1: into a converging beam to illuminate a sample. So essentially

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Speaker 1: you're focusing light on the smaller area that the sample

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Speaker 1: itself will sit on, and of course that is on

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Speaker 1: the part of the microscope that's called the stage. The

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Speaker 1: microscope has what is called an objective lens that's near

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Speaker 1: the end opposite where you put your eye, so this

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Speaker 1: is the end that's closest to the sample. Uh. The

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Speaker 1: lens that's close to your eye, by the way, is

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Speaker 1: fittingly called the ocular lens. So the objective lens and

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Speaker 1: the condenser are aligned to focus on the same spot

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Speaker 1: of a sample, so the light from the condenser is

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Speaker 1: hitting the same region of a sample that the objective

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Speaker 1: lens is focused on. The job of the objective lens

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Speaker 1: is to gather light from the point of observation and

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Speaker 1: focus that light to produce a real image. Objective lenses

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Speaker 1: are in stuff like cameras and telescopes to they're not

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Speaker 1: just in microscopes. The lenses in the eyepiece of the

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Speaker 1: microscope do the majority of the actual magnification. So with

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Speaker 1: light microscopes you can sometimes swap out the objective lens,

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Speaker 1: but rarely can you swap out the eye piece. Uh.

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Speaker 1: The reason you would swap out the objective lens is

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Speaker 1: because it does affect the magnification somewhat. A more flat

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Speaker 1: objective lens will have a lower magnification than a rounder

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Speaker 1: objective lens. This is all due to the physics of optics,

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Speaker 1: which I'm not going to go into here because without

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Speaker 1: visual aids, I would be struggling to describe them accurately.

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Speaker 1: The purpose of swapping out those objective lenses is to

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Speaker 1: focus on either larger or smaller areas of a sample.

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Speaker 1: So if you need to look at really small regions

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Speaker 1: of a sample, you'll want a rounder objective lens, and

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Speaker 1: this will let you look at the very tiny regions

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Speaker 1: of a sample. A comparison microscope is, like I said,

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Speaker 1: a pair of these light microscopes and allows you to

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Speaker 1: view two samples at the same time. That lets you

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Speaker 1: compare those two samples, and you can eliminate the necessity

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Speaker 1: to rely upon memory when comparing one sample with another,

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Speaker 1: and in the case of forensics, that's incredibly important. You

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Speaker 1: might be comparing a bullet that was retrieved from a

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Speaker 1: crime scene with a bullet that you have fired from

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Speaker 1: a firearm that you suspect was used at that crime scene.

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Speaker 1: So you want to see if these two bullets were

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Speaker 1: in fact fired out of the same firearm, and you

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Speaker 1: want to be able to compare the markings on bullet

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Speaker 1: one versus bullet Too. But if you were just having

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Speaker 1: to swap them out underneath the same microscope, you would

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Speaker 1: have to remember, all right, well, the markings I saw

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Speaker 1: on bullet one, do they match up to what I'm

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Speaker 1: seeing now in bullet too. With a comparison microscope, you

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Speaker 1: can look at them side by side in real time,

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Speaker 1: and that's much more reliable than looking at one sample

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Speaker 1: than removing it from the microscope, putting in a second

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Speaker 1: sample and then saying, huh, I think this looks the same.

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Speaker 1: So it it took a lot of ambiguity out of investigation. Now.

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Speaker 1: Light microscopes are really useful, but sometimes you gotta go

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Speaker 1: a little further than what light microscope can do. They

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Speaker 1: have limitations on the amount of magnification they can provide,

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Speaker 1: and that's where you might want to up your game

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Speaker 1: a bit go with something like a scanning electron microscope.

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Speaker 1: Those microscopes can magnify a sample up to three hundred

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Speaker 1: thousand times. It is an enormous amount of magnification. And

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Speaker 1: a scanning electron microscope can also have depth of field,

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Speaker 1: like really good depth of field, to the point where

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Speaker 1: you will end up with an image that is almost

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Speaker 1: three D in nature. The s c M can or

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Speaker 1: scanning electron microscope can tell researchers a lot about the

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Speaker 1: composition of a sample, so not just what it looks like,

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Speaker 1: but the stuff that it's made out of. So we

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Speaker 1: should talk about how these work because it's simple to

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Speaker 1: say scanning electron microscope, but what does that really mean. Well,

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Speaker 1: back in two scientists developed a precursor to this, called

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Speaker 1: the transmission electron microscope or t e M, and that

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Speaker 1: microscope would direct a beam of electrons through a sample

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Speaker 1: to create a projectable image. Scanning electron microscopes followed soon afterward.

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Speaker 1: They were developed in nineteen five, just a couple of

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Speaker 1: years later, and initially they didn't get a whole lot

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Speaker 1: of support in the scientific community. Uh, partly because the

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Speaker 1: transmission electron microscopes that just come out we're already seen

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Speaker 1: to have covered that territory. Scientists are saying, well, why

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Speaker 1: should we spend money developing this new technology. We already

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Speaker 1: have this other one that seems to do the same thing. Ultimately,

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Speaker 1: scanning electron microscope showed that they had features that made

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Speaker 1: them appealing on their own. So your basic scanning electron

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Speaker 1: microscope consists of the following parts, and it is very

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Speaker 1: different in many ways from a light microscope. You're not

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Speaker 1: looking through an eyepiece the way you would with a

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Speaker 1: light microscope. First of all, the entire guts of the

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Speaker 1: scanning electron microscope are inside a vacuum chamber. The microscope

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Speaker 1: itself is sealed in such a way that there is

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Speaker 1: a vacuum inside of it. And it has to be

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Speaker 1: like that because you're using electrons as you're scanning medium.

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Speaker 1: You don't want to have any interference from particles or

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Speaker 1: even air molecules. Those could be uh obstacles for an

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Speaker 1: electron beam and it would throw everything off if you

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Speaker 1: in fact had particles or air inside the microscope. So

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Speaker 1: it needs to be a vacuum. The really important element,

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Speaker 1: actually all of them are really important, but the business

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Speaker 1: element of the scanning electron microscope is the electron gun.

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Speaker 1: These are devices that produce a beam of electrons. It's

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Speaker 1: really not that different from old CRT televisions. Those have

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Speaker 1: electron guns that fire electrons at a phosphorus screen to

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Speaker 1: create the light that you would see on an old television,

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Speaker 1: but in this case, the electron gun creates a beam

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Speaker 1: of electrons to scan your sample. The most common version

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Speaker 1: of the electron gun that you will find is the

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Speaker 1: thermionic gun, which, as the name implies, has to do

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Speaker 1: with heat, right, thermal thermionic. So you heat up a filament.

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Speaker 1: You typically would use something like tungusten because as a

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Speaker 1: very high melting point, you heat it up really, really

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Speaker 1: really hot. And when you do that, when you pour

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Speaker 1: energy into it, you help it shed electrons. I've talked

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Speaker 1: about this before, where pouring energy into an atom means

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Speaker 1: that you're energizing those electrons. Electrons typically orbit and atoms

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Speaker 1: nucleus in energy shells, and by boosting the energy of

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Speaker 1: those electrons, they moved to higher and higher shells outside

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Speaker 1: of that nucleus, and if you pour in enough energy,

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Speaker 1: you can strip the electron away from the atom entirely.

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Speaker 1: So that's what you do with these electron guns. The

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Speaker 1: filament heats up to this incredible temperature and starts to

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Speaker 1: shed off electrons. And then you aim those electrons at

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Speaker 1: a sample. The other type of electron gun, by the way,

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Speaker 1: is the field emission gun, that uses strong electrical fields

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Speaker 1: to strip electrons away from their associated atoms. Electron guns,

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Speaker 1: whether they're thermionic or field emission guns, are located on

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Speaker 1: one end or the other of a scanning electron microscope.

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Speaker 1: They're either at the very top or at the very bottom.

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Speaker 1: Either way, they're doing the same thing. The lenses in

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Speaker 1: a scanning electron microscope are not optical lenses. They're not

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Speaker 1: ground glass lenses. The lenses in the scanning electron microscope

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Speaker 1: are actually magnets because magnets can shape the path of electrons.

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Speaker 1: Electrons have a charge, so using magnets you can attract

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Speaker 1: or repel electrons. This is how particle accelerators like the

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Speaker 1: large hadron collider work. They use these powerful electro magnets

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Speaker 1: to control the beam of charged particles protons or electrons.

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Speaker 1: The scanning electron microscope uses magnets to focus the beam

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Speaker 1: of electrons and control them and direct them to where

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Speaker 1: they need to go in order to scan a sample.

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Speaker 1: The scanning electron microscope also has a sample chamber. That's

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Speaker 1: where you actually place the specimen that you are scanning,

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Speaker 1: and since we're talking about crazy levels of magnification here,

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Speaker 1: you need that sample to be super still. Any movement,

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Speaker 1: any vibration is going to be magnified dramatically and it's

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Speaker 1: going to corrupt your results. So you want it to

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Speaker 1: be very stable, and typically that means insulating it against

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Speaker 1: all vibrations as much as you can. So if you

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Speaker 1: were to go to visit like a forensics lab, and

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Speaker 1: let's say it's a huge forensics lab, maybe it's an academy,

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Speaker 1: and it's got multiple floors, chances are you're going to

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Speaker 1: find the scanning electron microscopes on the ground floor, because

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Speaker 1: going up more than just the ground floor could potentially

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Speaker 1: introduce vibrations to your sample chamber and that would throw

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Speaker 1: off your results. The scanning electron microscope also has detectors.

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Speaker 1: Right you're you're blasting a sample with electrons, you have

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Speaker 1: to have detectors to pick up the response of that,

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Speaker 1: and those detectors include stuff like secondary electron detectors. Those

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Speaker 1: are detectors that can actually register electrons from the sample itself. So,

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Speaker 1: in other words, you're bombarding the sample with electrons from

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Speaker 1: your electron beam. Sometimes that dislodges electrons from the surface

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Speaker 1: of the outer surface of the sample, so the secondary

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Speaker 1: electron detectors can pick those up. But other detectors will

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Speaker 1: include back scatter detectors or X ray detectors. So when

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Speaker 1: you are scanning a specimen, the electron beam moves over

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Speaker 1: the surface of the object, and to do that, the

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Speaker 1: scanning electron microscope uses what are called scanning coils. These

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Speaker 1: are magnetic field generators that use fluctuating voltage to create

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Speaker 1: the magnetic field, and the scanning electron microscope uses that

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Speaker 1: to manipulate the electron beam. The coils direct the beam

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Speaker 1: across the specimen in a very tight grid like pattern,

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Speaker 1: so up and down, left and right, to get every

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Speaker 1: single point on the surface of that specimen. That does

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Speaker 1: dislodge electrons from the surface of the specimen in unique patterns,

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Speaker 1: so the secondary detector attracts those scattered electrons and then

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Speaker 1: registers those electrons as different levels of brightness on a monitor.

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Speaker 1: So the intensity of the brightness that you see in

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Speaker 1: the image will correspond with the number of electrons that

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Speaker 1: hit the detector. The detector quote unquote knows where secondary

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Speaker 1: electrons come from based upon the scanning beam's position, and

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Speaker 1: this can be shown in an optical image on a

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Speaker 1: video display. So think of for for the purposes of visualization,

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Speaker 1: imagine a laser beam it's hitting a single point on

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Speaker 1: a piece of cloth, let's say, And then imagine that

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Speaker 1: you have a sensor that can pick up when electrons

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Speaker 1: are being shot off by this piece of off. So

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Speaker 1: we're thinking of a laser beam as that's the electron beam.

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Speaker 1: We're just imagining it as a laser beam. You move

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Speaker 1: the laser beam across the sample, and the detector is

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Speaker 1: constantly picking up these electrons as they are shot off

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Speaker 1: by the sample. And because this is all happening at

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Speaker 1: essentially the speed of light, I mean, we're talking super fast,

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Speaker 1: you know where those electrons are coming from, because you

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Speaker 1: know what part of the sample the beam has just

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Speaker 1: made contact with. And that ends up being transmitted to

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Speaker 1: a computer system that interprets that and plots it as

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Speaker 1: pixels points of light on the monitor, and then you

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Speaker 1: get the computer image of what the scanning electron microscope

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Speaker 1: just scanned. It's pretty darn cool. Backscattered electrons are those

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Speaker 1: from the beam that reflect off the surface of the

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Speaker 1: specimen and a detector can pick up those as well,

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Speaker 1: and in a similar way constructive image. So backscatter. Those

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Speaker 1: are electrons that came from the electron beam, not we're

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Speaker 1: shed by the sample. And then the X ray detectors

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Speaker 1: pick up X rays that would be emitted from underneath

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Speaker 1: the specimen, and the beam scans the entirety of the

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Speaker 1: specimen and the detector's data is used to construct the

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Speaker 1: corresponding image. And that's how scanning electron microscopes work if

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Speaker 1: you really want to dive more into that technology, because

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Speaker 1: I realized again without visual aids it gets a little

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Speaker 1: challenging to understand. There's a great article on how stuff

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Speaker 1: works about how scanning electron microscopes work. Now, I'm gonna

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Speaker 1: take a quick break, and when I come back, we're

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Speaker 1: gonna look at some of the other cool technology used

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Speaker 1: in forensic science. Now, in the last episode, I talked

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Speaker 1: about ballistics and measuring stuff like bullet holes to determine

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Speaker 1: the angle and direction of firearm was pointed before firing.

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Speaker 1: And in the old days you do stuff like tape

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Speaker 1: measures to figure all that out, you know, take physical measurements,

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Speaker 1: but today you typically would use laser scanners, they can

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Speaker 1: give you much more precise information. A laser scanner depends

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Speaker 1: largely on the time of flight method. That's pretty much

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Speaker 1: similar to sonar and radar or speed guns that that

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Speaker 1: police use to detect the speed of a vehicle. The

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Speaker 1: whole idea is what what amount of time does it

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Speaker 1: take for a laser beam to travel from in the

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Speaker 1: mirror to a sensor. Right, So by knowing the amount

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Speaker 1: of time between when a pulse of lasers left a

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Speaker 1: laser and when they were picked up by a sensor,

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Speaker 1: you can know the distance it traveled. Because it's traveling

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Speaker 1: at the speed of light. That's a constant. You can

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Speaker 1: use that constant and then work backwards and determine how

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Speaker 1: far did this laser beam travel. With laser scanners, you're

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Speaker 1: talking about a detector built into the scanner itself, right,

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Speaker 1: So they go. You've got an a mitter and a

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Speaker 1: scanner and they're next to each other, and then you

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Speaker 1: take half the distance that you calculate. Because the beam

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Speaker 1: travels out, it hits an object, it travels back and

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Speaker 1: gets picked up by the sensor, So that means the

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Speaker 1: laser has traveled twice the distance between the point of

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Speaker 1: the laser and the the point of contact. So you

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Speaker 1: just take half of that that will tell you the distance. Right.

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Speaker 1: So you use these laser scanners uh the time of

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Speaker 1: flight scanners, and you move them in a grid fashion

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Speaker 1: to capture all points of a scanned specimen, and then

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Speaker 1: you get this this collection of data points that tells

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Speaker 1: you how far away the various parts of a specimen

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Speaker 1: were compared to the origin spot of the laser scanner.

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Speaker 1: That would allow you to then plot that information in

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Speaker 1: a computer and get a real good read on the

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Speaker 1: specifics of whatever it was you were scanning. At three

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Speaker 1: D dash forensic dot com, there's a description of this

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Speaker 1: technology used to investigate a shooting crime to have then Vallejo, California.

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Speaker 1: This one took place in there was a couple who

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Speaker 1: were in a car that was outside of a home

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Speaker 1: in California. An argument broke out, presumably between the couple

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Speaker 1: and maybe with someone else as well who was outside

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Speaker 1: the car on a porch in front of the house.

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Speaker 1: That person on that porch fired an a K forty

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Speaker 1: seven at the vehicle. One of the bullets struck and

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Speaker 1: killed the driver of that vehicle, but the person who

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Speaker 1: shot the a K forty seven later claimed that the

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Speaker 1: passenger of this car had a gun and the passenger

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Speaker 1: was threatening the person who was standing on the porch.

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Speaker 1: So in California, there is something called the provocative act doctrine,

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Speaker 1: which states that if someone incites a killing, if they

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Speaker 1: escalate a situation and then a killing occurs because of

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Speaker 1: that escalator, that person can be charged with murder. So

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Speaker 1: the passenger in this car could be charged with the

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Speaker 1: murder of the driver of that car because of this

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Speaker 1: provocative act. Even though the passenger in the car wasn't

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Speaker 1: the one who fired the gun, the argument would be

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Speaker 1: because of the passenger's actions, the driver died, so the

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Speaker 1: person charged is not the one who actually did the killing,

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Speaker 1: but incited the killing to happen. So the prosecution is

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Speaker 1: arguing the passengers actions lead to the death of this driver.

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Speaker 1: And at the heart of the issue was whether the

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Speaker 1: passenger actually did possess a gun and either threatened or

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Speaker 1: perhaps even fired it at the person who was on

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Speaker 1: the porch. The shooter who stood on that porch fired

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Speaker 1: an a K forty seven in full auto mode, which

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Speaker 1: means you just hold down the trigger and it will

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Speaker 1: keep firing until you let go of the trigger, You're

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Speaker 1: out of bullets. Investigators were brought in to answer quite is,

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Speaker 1: like where was the car when it was struck by

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Speaker 1: the two bullets? What is the line of sight from

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Speaker 1: the porch of the house to the position of the car.

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Speaker 1: If you assume the height of the person on the

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Speaker 1: porches about five ft eight inches, that was the height

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Speaker 1: of the shooter. What is the line of sight from

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Speaker 1: the front passenger position to the porch, Because if the

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Speaker 1: person in the passenger seat was actually threatening the person

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Speaker 1: on the porch, they would have to be able to

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Speaker 1: see that person. Was the vehicle in motion? If so,

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Speaker 1: how fast was it going? And could the investigators determine

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Speaker 1: the order of the two bullets that struck the car?

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Speaker 1: Which one was first? The three D laser scan that

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Speaker 1: the investigators used, uh, they made one of the bullet holes,

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Speaker 1: they did of the car, the porch. They actually scanned

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Speaker 1: the whole area, but they were looking at the bullet

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Speaker 1: holes first, and that indicated that the two bullets that

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Speaker 1: were both shot from the same angle, which indicated that

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Speaker 1: the shooters stood in the same spot while firing the shots.

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Speaker 1: But there were there was a distance between bullet hole

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Speaker 1: number one and bullet hole number two, and that distance

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Speaker 1: would mean that the car must have moved two point

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Speaker 1: seven feet between those two shots. And the reason they

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Speaker 1: realized that the car was the one that moved and

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Speaker 1: not the person was because the a K forty seven

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Speaker 1: was fired in full auto mode. The time between two

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Speaker 1: shots from a cold start would be about one tenth

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Speaker 1: of a second, which means the car must have moved

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Speaker 1: to get two point seven feet further in one tenth

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Speaker 1: of a second. That's way too fast for a person

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Speaker 1: to have moved and been able to fire this gun,

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Speaker 1: and it would mean that the car was moving at

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Speaker 1: around a little less than twenty miles per hour. The

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Speaker 1: investigators ended up conducting thorough laser scans not just in

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Speaker 1: the vehicle, but the whole area where the crime occurred,

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Speaker 1: and at the heart of the issue was conflicting testimony.

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Speaker 1: Did the passenger have a gun? Was the passenger threatening

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Speaker 1: or actively shooting the person on the porch? And based

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Speaker 1: on the scans and simulations, the jury found the evidence

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Speaker 1: did not support the shooters claim that the passenger was

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Speaker 1: threatening the shooter with a gun, and so the charges

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Speaker 1: of murder against the passenger were dismissed. So that's kind

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Speaker 1: of an interesting way of using laser scanners. It's a

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Speaker 1: pretty fascinating discussion. And again, if you go to that

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Speaker 1: website three D dash forensic dot com, you can find

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Speaker 1: the whole case study written up and in greater detail

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Speaker 1: and learn more about it. So let's say let's change

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Speaker 1: gears a little bit. Let's say you go to a

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Speaker 1: crime scene and there's broken glass everywhere, and the cops

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Speaker 1: have a suspect and custody, and a close examination of

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Speaker 1: the suspect's clothing revealed that there were some glass particles

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Speaker 1: that were attached to that clothing. They were they were

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Speaker 1: just stuck on there. But the particles are really small,

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Speaker 1: and it's not obvious that they come from the crime scene.

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Speaker 1: They might be unrelated. So if you've got really small

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Speaker 1: glass particles, they're so small that you can't just you know,

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Speaker 1: piece them together, how can you determine whether or not

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Speaker 1: they came from the crime scene. Well, you could call

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Speaker 1: in the laser ablation inductively coupled plasma mass spectrometry device.

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Speaker 1: It's also known as the l A I C p MS.

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Speaker 1: One of those cases where the acronym is almost as

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Speaker 1: clunky as the full name. It sounds like something out

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Speaker 1: of Ghostbusters, doesn't it. But this is a Once you

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Speaker 1: break it down into its component parts, it's a lot

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Speaker 1: easier to understand because when you hear laser ablation inductively

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Speaker 1: coupled plasma mass spectrometry, that seems like it would be insane,

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Speaker 1: but it actually makes a lot more sense when you

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Speaker 1: break it down. So first, let's talk about laser ablation.

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Speaker 1: This is where you use a laser beam that is

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Speaker 1: of a particular strength so that when you move it

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Speaker 1: across a sample surface, it generates fine particles. Through laser ablation, essentially,

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Speaker 1: you're shaving off particles from the sample. You gather these

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Speaker 1: particles and they go into a chamber where an inductively

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Speaker 1: coupled plasma instrument otherwise known as a plasma torch ionizes

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Speaker 1: the particles. Once again, you uh impart a lot of

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Speaker 1: energy to the particles, so it ends up ionizing them.

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00:24:16,880 --> 00:24:20,640
Speaker 1: It sheds electrons, it becomes charged, and then you put

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Speaker 1: it through a spectrometer. The spectrometer separates the ions using filters,

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00:24:26,720 --> 00:24:30,400
Speaker 1: which aren't physical filters. It's not like a mesh or something.

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Speaker 1: There in the form of first an electric field and

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00:24:34,080 --> 00:24:37,320
Speaker 1: then a magnetic field, and this forces the ions to

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00:24:37,840 --> 00:24:43,360
Speaker 1: fan out into a spectrum, and the ions will all

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00:24:44,080 --> 00:24:49,600
Speaker 1: fan out based upon physical uh features of those ions,

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Speaker 1: So all like ions will end up in one part

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Speaker 1: of the spectrum and unlike ions will be in a

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Speaker 1: different part of the spectrum. So by looking at the

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Speaker 1: whole spread of the spectrum, you can say what that

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Speaker 1: substance was made out of. A detector will count up

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Speaker 1: the ions and the various parts of the spectrum, and

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Speaker 1: a computer program analyzes the results to tell you what

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Speaker 1: it was that you zapped. And by analyzing a sample

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00:25:12,800 --> 00:25:15,480
Speaker 1: from a crime scene and then comparing those results to

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Speaker 1: samples collected from a suspect, you can see if the

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00:25:18,520 --> 00:25:21,159
Speaker 1: glass was made out of the same stuff, and if

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Speaker 1: it is, that's a clue that your suspect is someone

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00:25:23,560 --> 00:25:26,879
Speaker 1: to look at very carefully, as that match suggests that

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Speaker 1: they must have come in contact with the crime scene.

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Speaker 1: Now it's not it's not like smoking gun evidence, but

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Speaker 1: it certainly suggests if there's a match, that they were

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Speaker 1: involved in some way. Uh. If there's not a match,

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Speaker 1: then you could say, well, according to our results the glass, Yes,

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Speaker 1: you found glass on this person's clothing, but it doesn't

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Speaker 1: match the glass that was found at the crime scene,

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Speaker 1: so we can't say for certain that there was any

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Speaker 1: connection there. That actually suggests there's not a connection. Then

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Speaker 1: we can move on to stuff like document examination. This

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00:26:00,200 --> 00:26:03,639
Speaker 1: is where you're looking for, uh, any evidence that was

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00:26:03,720 --> 00:26:06,520
Speaker 1: left behind in kind of writing form, whether it was

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00:26:07,000 --> 00:26:11,400
Speaker 1: you know, handwriting or typing or printers whatever that maybe.

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Speaker 1: And this can be used in all sorts of crimes,

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Speaker 1: not just the kind of violent crimes I've sort of

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Speaker 1: talked about before, but all certainly like corporate crimes, you know,

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Speaker 1: that kind of stuff. So there's a lot of different

435
00:26:24,560 --> 00:26:27,919
Speaker 1: ways of doing this. One way is to look for

436
00:26:28,000 --> 00:26:32,000
Speaker 1: indented writing, you know, the idea that there's traces of

437
00:26:32,040 --> 00:26:35,840
Speaker 1: someone having written something. It's not necessarily on a piece

438
00:26:35,880 --> 00:26:38,160
Speaker 1: of paper. They're looking at maybe a piece of paper

439
00:26:38,160 --> 00:26:41,040
Speaker 1: that was underneath the one that was being written on.

440
00:26:41,920 --> 00:26:44,360
Speaker 1: Typically you would want to use something like oblique light

441
00:26:44,440 --> 00:26:49,200
Speaker 1: and photography first. In other words, you're hitting the surface

442
00:26:49,600 --> 00:26:54,560
Speaker 1: of the material that you suspect has indentations from previous

443
00:26:54,560 --> 00:26:57,840
Speaker 1: writing with light from different angles in order to try

444
00:26:57,840 --> 00:27:00,840
Speaker 1: and illuminate those indentations, and then you take pictures of it.

445
00:27:01,359 --> 00:27:06,000
Speaker 1: But there's also a device called an electrostatic detection apparatus

446
00:27:06,160 --> 00:27:09,080
Speaker 1: or E s d A that you can use. And

447
00:27:09,400 --> 00:27:11,240
Speaker 1: you know, when you write on a top sheet of paper.

448
00:27:11,320 --> 00:27:12,760
Speaker 1: Let's say you've got a pad of paper and you're

449
00:27:12,760 --> 00:27:16,040
Speaker 1: writing on that top sheet, you might see that you've

450
00:27:16,040 --> 00:27:21,440
Speaker 1: got indentations on the lower sheets and uh, and you

451
00:27:21,560 --> 00:27:24,680
Speaker 1: would use a pencil to shade out those indentations to

452
00:27:24,800 --> 00:27:27,399
Speaker 1: read writing. You see that in a lot of detective shows,

453
00:27:27,480 --> 00:27:30,159
Speaker 1: right a detective sees a pad of paper next to

454
00:27:30,160 --> 00:27:33,360
Speaker 1: a phone, picks up the pad of paper, grabs a pencil,

455
00:27:33,760 --> 00:27:37,240
Speaker 1: shades the pencil across the pad of paper, and spells

456
00:27:37,240 --> 00:27:42,560
Speaker 1: how the message like see pick up bag at third

457
00:27:42,600 --> 00:27:45,919
Speaker 1: and Broad Street or something like that. And you're like, oh, okay,

458
00:27:45,960 --> 00:27:51,160
Speaker 1: well voila. E s d A takes a slightly more

459
00:27:51,200 --> 00:27:56,119
Speaker 1: electrifying approach to this concept. So an E s d

460
00:27:56,240 --> 00:28:00,600
Speaker 1: A device generates an electro static field, and think of

461
00:28:00,600 --> 00:28:03,560
Speaker 1: it like, you know, uh, static electricity, that idea of

462
00:28:03,600 --> 00:28:07,919
Speaker 1: building up this charge. It imparts this electrostatic charge to

463
00:28:08,040 --> 00:28:11,760
Speaker 1: a document that could have indentations on it. So these

464
00:28:11,800 --> 00:28:15,080
Speaker 1: machines have a platform made out of bronze plate. You

465
00:28:15,119 --> 00:28:17,640
Speaker 1: put the piece of paper you're gonna scan on top

466
00:28:17,680 --> 00:28:20,440
Speaker 1: of that bronze plate on top of the piece of paper,

467
00:28:20,480 --> 00:28:24,159
Speaker 1: you put a thin layer of film on there, and

468
00:28:24,200 --> 00:28:28,200
Speaker 1: then you pass a highly charged wire called a corona

469
00:28:28,600 --> 00:28:33,000
Speaker 1: over the paper. And it's this highly charged wire that

470
00:28:33,400 --> 00:28:38,080
Speaker 1: imparts an electrostatic charge to the paper underneath. The indented

471
00:28:38,160 --> 00:28:41,640
Speaker 1: parts of the paper received the largest amount of that

472
00:28:41,720 --> 00:28:47,080
Speaker 1: electro static charge. Then once that's over, they can expose

473
00:28:47,200 --> 00:28:51,240
Speaker 1: the film covered paper to toner, and the toner also

474
00:28:51,280 --> 00:28:54,600
Speaker 1: has an electrostatic charge, but it's opposite to the charge

475
00:28:54,640 --> 00:28:57,240
Speaker 1: that the corona gave the paper, and opposite charges a

476
00:28:57,360 --> 00:29:01,200
Speaker 1: tract So the indented spots with the greatest amount of

477
00:29:01,280 --> 00:29:04,520
Speaker 1: charge attract the toner. Then you can see where the

478
00:29:04,560 --> 00:29:06,840
Speaker 1: invitations were. You can see them more clearly. You might

479
00:29:06,880 --> 00:29:09,240
Speaker 1: be able to read stuff. It's really not that different

480
00:29:09,320 --> 00:29:11,760
Speaker 1: from the way a photocopier works, if you remember my

481
00:29:11,800 --> 00:29:13,680
Speaker 1: episodes about that. So I thought that was a pretty

482
00:29:13,680 --> 00:29:17,640
Speaker 1: cool technology. Sometimes, however, you're not just looking for evidence

483
00:29:17,640 --> 00:29:19,880
Speaker 1: that someone has actually written something on a piece of paper.

484
00:29:19,920 --> 00:29:22,760
Speaker 1: You might want to determine if a document has been altered.

485
00:29:23,280 --> 00:29:27,120
Speaker 1: For example, let's say someone's signed a contract and then

486
00:29:27,520 --> 00:29:30,280
Speaker 1: later on they come to a court and they say

487
00:29:30,440 --> 00:29:34,040
Speaker 1: the contract I signed is different from the one that

488
00:29:34,080 --> 00:29:37,000
Speaker 1: they claim I signed. They must have changed it after

489
00:29:37,040 --> 00:29:40,280
Speaker 1: I signed it. They might want to use something like

490
00:29:40,320 --> 00:29:44,960
Speaker 1: a video spectral comparator device what the heck also called

491
00:29:44,960 --> 00:29:48,600
Speaker 1: a VSC. So this is an imaging device. It combines

492
00:29:48,680 --> 00:29:53,080
Speaker 1: multiple cameras, multiple sensors, and different lights to examine a

493
00:29:53,160 --> 00:29:57,720
Speaker 1: document and the entire spectrum of light, including ultra violet

494
00:29:57,800 --> 00:30:01,240
Speaker 1: and infrared that's beyond the visit spectrum, right We humans

495
00:30:01,320 --> 00:30:06,120
Speaker 1: can't see that without technological aid, so a computer is

496
00:30:06,160 --> 00:30:09,800
Speaker 1: able to render the results in shades we can see.

497
00:30:10,160 --> 00:30:13,600
Speaker 1: So you've got these cameras that can pick up in

498
00:30:13,640 --> 00:30:16,720
Speaker 1: these different frequencies, You've got lights in these different frequencies,

499
00:30:16,720 --> 00:30:20,560
Speaker 1: and sensors in these different frequencies, and through all this

500
00:30:20,680 --> 00:30:23,280
Speaker 1: you can analyze the data coming back and a computer

501
00:30:23,520 --> 00:30:26,920
Speaker 1: can present it in a way that we can actually see.

502
00:30:27,600 --> 00:30:31,240
Speaker 1: And the analysis of color is really important as it

503
00:30:31,280 --> 00:30:34,920
Speaker 1: can detect when two different but similar incs were used

504
00:30:34,920 --> 00:30:38,480
Speaker 1: on a document. So to our eyes, we might look

505
00:30:38,480 --> 00:30:40,400
Speaker 1: at the document and say, well, this was clearly all

506
00:30:40,440 --> 00:30:43,480
Speaker 1: written at the same time. We can put it through

507
00:30:43,720 --> 00:30:47,720
Speaker 1: a an analysis like this, where you're using different wavelengths

508
00:30:47,720 --> 00:30:52,960
Speaker 1: of light to analyze the document, and by taking precise

509
00:30:53,040 --> 00:30:56,120
Speaker 1: measurements of the light that's coming off that document that's

510
00:30:56,160 --> 00:31:00,640
Speaker 1: being reflected back from that document, you could say, well, actually,

511
00:31:01,240 --> 00:31:03,360
Speaker 1: it turns out there are two different inks that were

512
00:31:03,440 --> 00:31:06,280
Speaker 1: used on this document, which indicates that there were as,

513
00:31:06,320 --> 00:31:08,720
Speaker 1: there was a point where it stopped and started up,

514
00:31:08,760 --> 00:31:13,120
Speaker 1: and it was printed on a different device, and uh

515
00:31:13,400 --> 00:31:17,200
Speaker 1: so to casual glance, it might look like this was

516
00:31:17,240 --> 00:31:19,000
Speaker 1: all done at once, but you could say, well, no,

517
00:31:19,120 --> 00:31:22,400
Speaker 1: the analysis shows there's two different inks here. They look

518
00:31:22,520 --> 00:31:24,840
Speaker 1: the same to our human eyes, but when we put

519
00:31:24,880 --> 00:31:26,640
Speaker 1: it through the vs C, we can clearly see that

520
00:31:26,680 --> 00:31:29,080
Speaker 1: there were two different types of ink. So it's really

521
00:31:29,120 --> 00:31:31,840
Speaker 1: helpful if you want to see if in fact the

522
00:31:31,880 --> 00:31:36,280
Speaker 1: document has been changed, if something has been erased or replaced.

523
00:31:37,320 --> 00:31:40,760
Speaker 1: Very interesting technology. Well, I've got some more that I

524
00:31:40,800 --> 00:31:45,000
Speaker 1: want to talk about in the great world of forensic tech.

525
00:31:45,440 --> 00:31:47,320
Speaker 1: But before I get to that, let's take another quick

526
00:31:47,360 --> 00:31:57,120
Speaker 1: break to thank our sponsors. I just talked a bit

527
00:31:57,160 --> 00:31:59,840
Speaker 1: about devices that use cameras. Might as well stick with

528
00:32:00,000 --> 00:32:03,160
Speaker 1: cameras because photography is a really important part of forensic science.

529
00:32:03,920 --> 00:32:08,960
Speaker 1: Let's say there's a case where a forensic nurse, and

530
00:32:09,000 --> 00:32:11,640
Speaker 1: there are such things. A forensic nurse is called in

531
00:32:12,080 --> 00:32:15,280
Speaker 1: to treat someone who appears to be the victim of

532
00:32:15,320 --> 00:32:19,240
Speaker 1: a physical attack. This person might not be communicative, and

533
00:32:19,280 --> 00:32:21,040
Speaker 1: this can be a matter of life and death. And

534
00:32:21,120 --> 00:32:25,400
Speaker 1: sometimes evidence of physical harm is hard to see, particularly

535
00:32:25,840 --> 00:32:30,280
Speaker 1: if that harm happened just a short time earlier. So uh,

536
00:32:30,440 --> 00:32:34,640
Speaker 1: for example, there might not be evidence of bruising that

537
00:32:35,080 --> 00:32:39,440
Speaker 1: it's that's visibly. Uh, they're right, but there may very

538
00:32:39,440 --> 00:32:42,000
Speaker 1: well be damaged that will lead to that. So there

539
00:32:42,040 --> 00:32:44,920
Speaker 1: are cameras that make use of a technology called alternative

540
00:32:45,120 --> 00:32:48,920
Speaker 1: light source photography that can reveal evidence of physical harms

541
00:32:48,920 --> 00:32:52,840
Speaker 1: such as bruising, before they become visible, and it allows

542
00:32:52,840 --> 00:32:56,400
Speaker 1: medical staff to treat a person quickly, and sometimes that

543
00:32:56,400 --> 00:33:00,160
Speaker 1: can be the difference between saving someone and losing them. Now,

544
00:33:00,240 --> 00:33:03,560
Speaker 1: it's called alternative light source photography because those cameras may

545
00:33:03,640 --> 00:33:06,840
Speaker 1: use something like infrared light or ultra violet light, or

546
00:33:06,880 --> 00:33:08,920
Speaker 1: they might even use visible light, but it's in a

547
00:33:09,040 --> 00:33:13,080
Speaker 1: very particular wavelength. For example, I saw one version of

548
00:33:13,120 --> 00:33:16,880
Speaker 1: such a camera that uses blue light to illuminate a

549
00:33:16,960 --> 00:33:21,000
Speaker 1: person's skin and then has a special orange filter to

550
00:33:21,760 --> 00:33:24,000
Speaker 1: try and pick up any evidence of physical harm that

551
00:33:24,120 --> 00:33:27,360
Speaker 1: might not be visible under normal lighting conditions, which I

552
00:33:27,360 --> 00:33:30,600
Speaker 1: thought was really interesting. They're also high speed cameras that

553
00:33:30,640 --> 00:33:34,280
Speaker 1: are frequently used to get a better understanding of ballistics evidence.

554
00:33:34,560 --> 00:33:37,800
Speaker 1: High speed cameras can take images at incredible speeds, as

555
00:33:37,800 --> 00:33:41,440
Speaker 1: the name suggests, and typically that requires a lot of light.

556
00:33:41,640 --> 00:33:45,440
Speaker 1: You don't really use high speed cameras and low light conditions,

557
00:33:45,680 --> 00:33:49,000
Speaker 1: and that's because cameras work by focusing light coming through

558
00:33:49,000 --> 00:33:52,640
Speaker 1: a lens through an opening called the aperture, which can

559
00:33:52,640 --> 00:33:55,640
Speaker 1: open or shrink. If you open, you allow more light

560
00:33:55,640 --> 00:33:57,600
Speaker 1: to come through. If you shrink, you allow less light

561
00:33:57,640 --> 00:34:00,600
Speaker 1: to come through. And you have a shutter. The shutter

562
00:34:00,880 --> 00:34:04,400
Speaker 1: is a device that opens and closes and allows the

563
00:34:04,600 --> 00:34:08,600
Speaker 1: light to either pass through and expose an image on film,

564
00:34:08,800 --> 00:34:14,359
Speaker 1: or it hits a digital sensor, right for for digital photography.

565
00:34:14,480 --> 00:34:18,200
Speaker 1: With high speed photography, this has to happen really really fast.

566
00:34:18,640 --> 00:34:22,440
Speaker 1: Right You're you're creating images at an incredible rate, So

567
00:34:22,480 --> 00:34:24,200
Speaker 1: the shutter has to be able to open and close

568
00:34:24,400 --> 00:34:26,960
Speaker 1: super super fast, and that means you have to have

569
00:34:27,000 --> 00:34:29,239
Speaker 1: a very well lit scene because the shutter is just

570
00:34:29,320 --> 00:34:32,319
Speaker 1: allowing light through or not allowing light through, and if

571
00:34:32,360 --> 00:34:34,880
Speaker 1: it's moving super super fast, not a whole lot of

572
00:34:34,920 --> 00:34:37,400
Speaker 1: light gets through on each time it opens, So you

573
00:34:37,440 --> 00:34:40,560
Speaker 1: want to have a very bright scene in order to

574
00:34:40,560 --> 00:34:44,280
Speaker 1: be able to see anything. Otherwise the video or film

575
00:34:44,360 --> 00:34:46,480
Speaker 1: that you take is going to be very very dark.

576
00:34:46,920 --> 00:34:50,240
Speaker 1: There's also a thing called a gunshot residue scanning electron

577
00:34:50,400 --> 00:34:53,840
Speaker 1: microscope as another detection tool that can help look for

578
00:34:53,920 --> 00:34:56,680
Speaker 1: a gunshot residue. No big surprise based on the name.

579
00:34:57,280 --> 00:35:02,120
Speaker 1: It's actually a combination of hardware in software, and typically

580
00:35:02,160 --> 00:35:04,840
Speaker 1: these things look like big desktop computers, you know, with

581
00:35:04,880 --> 00:35:07,960
Speaker 1: a couple of monitors, big tower. There might be some

582
00:35:08,000 --> 00:35:10,520
Speaker 1: specialized peripherals attached to it, but you know, if you

583
00:35:10,600 --> 00:35:12,359
Speaker 1: looked at a casual glance, you might just say, oh,

584
00:35:12,400 --> 00:35:15,680
Speaker 1: that's just a desktop computer. The microscope works like the

585
00:35:15,760 --> 00:35:19,360
Speaker 1: scanning electron microscopes i mentioned earlier, looking for any suspicious

586
00:35:19,360 --> 00:35:21,960
Speaker 1: particles that could be the residue from a firearm discharging,

587
00:35:22,200 --> 00:35:25,520
Speaker 1: and then the system uses spectroscopy to identify what those

588
00:35:25,520 --> 00:35:28,800
Speaker 1: particles are. So both the technologies are referred to earlier

589
00:35:28,800 --> 00:35:32,120
Speaker 1: in this episode would be combined in this kind of

590
00:35:32,160 --> 00:35:38,840
Speaker 1: approach to first look at very closely a material that

591
00:35:38,920 --> 00:35:42,399
Speaker 1: you suspect might have gunshot residue on it, and then

592
00:35:42,480 --> 00:35:46,680
Speaker 1: through spectroscopy, do this analysis to determine are there, in

593
00:35:46,719 --> 00:35:50,520
Speaker 1: fact any particles there that would indicate gunshot residue. On

594
00:35:50,600 --> 00:35:54,560
Speaker 1: TV and movies, we often see investigators using technology like

595
00:35:54,640 --> 00:35:59,120
Speaker 1: three D facial reconstruction technology UH. The technique uses algorithms

596
00:35:59,160 --> 00:36:02,560
Speaker 1: to determine what someone might have looked like based upon

597
00:36:02,719 --> 00:36:08,840
Speaker 1: typically remains. It's pretty grim stuff, so you find remains

598
00:36:08,840 --> 00:36:11,319
Speaker 1: at a scene, maybe you find skeletal remains, and you

599
00:36:11,360 --> 00:36:13,680
Speaker 1: wonder what did the person look like in life, and

600
00:36:13,719 --> 00:36:17,280
Speaker 1: you're trying to reconstruct that that That technology really does exist,

601
00:36:17,920 --> 00:36:21,720
Speaker 1: though it has shown to be variable in its reliability

602
00:36:22,080 --> 00:36:25,920
Speaker 1: depending upon the actual implementation. It doesn't always work perfectly,

603
00:36:26,440 --> 00:36:30,759
Speaker 1: and it depends heavily upon the software packages that you use. Typically,

604
00:36:31,120 --> 00:36:35,719
Speaker 1: you would use software UH to analyze a scan of

605
00:36:35,760 --> 00:36:39,799
Speaker 1: the remains, So you're using scanners to completely get a

606
00:36:39,960 --> 00:36:45,279
Speaker 1: very detailed representation of those remains, and the software would

607
00:36:45,280 --> 00:36:48,279
Speaker 1: then go over that information, and you might also have

608
00:36:48,360 --> 00:36:51,360
Speaker 1: to include other information you might have about the person,

609
00:36:51,800 --> 00:36:55,640
Speaker 1: like if you know anything about their age, their gender, UH,

610
00:36:55,800 --> 00:36:58,720
Speaker 1: their ancestry. All of that could be taken into account

611
00:36:58,760 --> 00:37:01,279
Speaker 1: by the software package while it's trying to build out

612
00:37:01,680 --> 00:37:05,320
Speaker 1: what the person might have looked like, uh, in life.

613
00:37:06,000 --> 00:37:10,040
Speaker 1: And then you might feed the software some images of say,

614
00:37:10,080 --> 00:37:12,799
Speaker 1: missing persons. Let's say that you've got a file of

615
00:37:12,880 --> 00:37:16,800
Speaker 1: people who have gone missing. You might feed those images

616
00:37:16,800 --> 00:37:19,640
Speaker 1: through to see if the computer system can find any

617
00:37:19,640 --> 00:37:26,160
Speaker 1: matches between the reconstruction that's created and any actual humans

618
00:37:26,200 --> 00:37:28,719
Speaker 1: that you have pictures of, and if there are any

619
00:37:28,719 --> 00:37:33,000
Speaker 1: matches that would allow you to help narrow down your investigation. Potentially,

620
00:37:33,040 --> 00:37:38,719
Speaker 1: it doesn't. Again, it's not necessarily a hit, but it

621
00:37:38,760 --> 00:37:41,920
Speaker 1: could mean that you are you've got a lead to follow.

622
00:37:42,360 --> 00:37:44,440
Speaker 1: As I said, the reliability of the software depends upon

623
00:37:44,480 --> 00:37:48,919
Speaker 1: the actual software package used, so it's it's not infallible.

624
00:37:49,320 --> 00:37:51,880
Speaker 1: We also see a lot of news about DNA evidence,

625
00:37:51,920 --> 00:37:54,480
Speaker 1: which is really important stuff. Let's say you recover some

626
00:37:54,560 --> 00:37:57,279
Speaker 1: DNA evidence at a crime scene that doesn't match any

627
00:37:57,320 --> 00:37:59,719
Speaker 1: of the known people to have been there, right, so

628
00:37:59,760 --> 00:38:02,200
Speaker 1: what or it's a violent crime or not. You find

629
00:38:02,200 --> 00:38:06,120
Speaker 1: some DNA evidence, you've eliminated the people who typically are

630
00:38:06,200 --> 00:38:09,879
Speaker 1: at that place, and you want to know who the

631
00:38:09,920 --> 00:38:13,759
Speaker 1: heck does this DNA belong to, It could belong to

632
00:38:13,800 --> 00:38:16,440
Speaker 1: the perpetrator of a crime. So you take the DNA

633
00:38:16,640 --> 00:38:20,080
Speaker 1: in for analysis. You first replicate that DNA millions of

634
00:38:20,120 --> 00:38:22,279
Speaker 1: times for the purposes of testing, so that you have

635
00:38:22,440 --> 00:38:24,799
Speaker 1: enough of it to work with, and then you analyze it.

636
00:38:25,239 --> 00:38:29,480
Speaker 1: And scientists can use phenotyping to identify genetic markers and

637
00:38:29,600 --> 00:38:34,280
Speaker 1: DNA variants and based upon that information make predictions about

638
00:38:34,280 --> 00:38:37,440
Speaker 1: the appearance of the person who that DNA belongs to.

639
00:38:37,600 --> 00:38:41,760
Speaker 1: These predictions are very general, so they're also based off probabilities.

640
00:38:42,280 --> 00:38:45,160
Speaker 1: Nothing is totally certain. You can't just scan the DNA

641
00:38:45,200 --> 00:38:47,759
Speaker 1: and say, ah, I know exactly what this person looks like,

642
00:38:48,080 --> 00:38:52,440
Speaker 1: but you can get some general predictions. There's a couple

643
00:38:52,400 --> 00:38:55,640
Speaker 1: of different systems that can do this. There's one in particular,

644
00:38:55,719 --> 00:38:59,840
Speaker 1: the hi risplex system that I read about. According to

645
00:39:00,080 --> 00:39:04,600
Speaker 1: what I read, it can predict blonde hair. Uh. If

646
00:39:04,680 --> 00:39:06,680
Speaker 1: it's got the markers for blonde hair, it can predict

647
00:39:06,760 --> 00:39:09,160
Speaker 1: whether the person has blonde hair about sixty nine five

648
00:39:09,200 --> 00:39:11,400
Speaker 1: percent at the time. Now, blonde hair that's carried by

649
00:39:11,400 --> 00:39:14,840
Speaker 1: a recessive gene, it's not really surprising that the success

650
00:39:14,960 --> 00:39:18,160
Speaker 1: rate is below. Brown hair gets a much higher hit

651
00:39:18,239 --> 00:39:21,160
Speaker 1: rate at seventy eight point five percent, red hair even

652
00:39:21,320 --> 00:39:24,320
Speaker 1: higher at eight percent, and black hair gets the highest

653
00:39:24,360 --> 00:39:28,120
Speaker 1: at eighty seven point five. The system can also use

654
00:39:28,239 --> 00:39:30,959
Speaker 1: the same sort of methodology to predict what color eyes

655
00:39:31,080 --> 00:39:35,200
Speaker 1: the person probably has, and so then if that's all

656
00:39:35,239 --> 00:39:37,040
Speaker 1: you have to go on, if there are no why witnesses,

657
00:39:37,120 --> 00:39:39,279
Speaker 1: but you have some DNA evidence, you could say, well,

658
00:39:39,320 --> 00:39:44,640
Speaker 1: based upon our analysis, there's the x amount of chance

659
00:39:44,760 --> 00:39:48,360
Speaker 1: the person has brown hair and blue eyes, and so

660
00:39:48,560 --> 00:39:51,080
Speaker 1: that at least gives you some parameters you can start

661
00:39:51,120 --> 00:39:54,120
Speaker 1: to look for when you're doing your investigation, although again

662
00:39:54,520 --> 00:39:57,400
Speaker 1: you have to remember these are all based on probabilities,

663
00:39:57,560 --> 00:40:01,440
Speaker 1: not certainties. And this next one goes out to all

664
00:40:01,480 --> 00:40:03,600
Speaker 1: you gamers out there. We live in an age where

665
00:40:03,640 --> 00:40:06,400
Speaker 1: there are numerous ways to store electronic data. You might

666
00:40:06,440 --> 00:40:10,480
Speaker 1: have a computer, a smartphone, a tablet, USB drives, hard drives,

667
00:40:10,840 --> 00:40:13,920
Speaker 1: optical discs. If you're clinging to the past, you might

668
00:40:14,000 --> 00:40:16,520
Speaker 1: use cloud storage. But one device that sometimes can be

669
00:40:16,640 --> 00:40:19,520
Speaker 1: used to store incriminating information is the good old game

670
00:40:19,640 --> 00:40:23,120
Speaker 1: console like the Xbox, and a moded Xbox can be

671
00:40:23,239 --> 00:40:26,080
Speaker 1: used to store all sorts of information of questionable legality,

672
00:40:26,239 --> 00:40:29,480
Speaker 1: not to mention stuff that's just outright illegal, and uh

673
00:40:29,760 --> 00:40:33,080
Speaker 1: mods can exploit known vulnerabilities in the Xbox. You don't

674
00:40:33,120 --> 00:40:36,759
Speaker 1: necessarily have to crack the Xbox open and do some

675
00:40:36,920 --> 00:40:39,920
Speaker 1: soldering to change things. There was one example that was

676
00:40:40,000 --> 00:40:44,040
Speaker 1: cited in a paper titled x f T, a Forensic

677
00:40:44,160 --> 00:40:48,000
Speaker 1: Analysis Tool for the Microsoft Xbox Game Console. It was

678
00:40:48,040 --> 00:40:51,680
Speaker 1: written by a guy named David Collins, and he pointed

679
00:40:51,719 --> 00:40:54,239
Speaker 1: out that there was an Xbox game Double O seven

680
00:40:54,360 --> 00:40:58,200
Speaker 1: Agent under Fire that had a vulnerability. An Xbox owner

681
00:40:58,680 --> 00:41:01,560
Speaker 1: could visit a link and download an exploit that was

682
00:41:01,600 --> 00:41:04,880
Speaker 1: created by a hacker. The exploit used the buffer overrun

683
00:41:05,120 --> 00:41:09,680
Speaker 1: vulnerability in that game for the saving process. So on

684
00:41:09,800 --> 00:41:12,360
Speaker 1: the Xbox, it would look like it was a valid

685
00:41:12,960 --> 00:41:15,880
Speaker 1: saved game. That's what the file would look like. It's like, oh, well,

686
00:41:15,920 --> 00:41:18,040
Speaker 1: that's just that's just a save game file, But in

687
00:41:18,160 --> 00:41:21,239
Speaker 1: reality it would be an operating environment. The Xbox owner

688
00:41:21,320 --> 00:41:24,120
Speaker 1: could use that operating environment to browse files using the

689
00:41:24,239 --> 00:41:27,800
Speaker 1: FTP protocol and download files to the Xbox and the

690
00:41:27,880 --> 00:41:31,279
Speaker 1: guys of this save file, so on casual glance, it

691
00:41:31,320 --> 00:41:35,399
Speaker 1: wouldn't look like anything was hinky. Now, the Xbox used

692
00:41:35,400 --> 00:41:38,440
Speaker 1: a file system called f a t X that is

693
00:41:38,560 --> 00:41:42,600
Speaker 1: not readable by most forensic software. So let's say you're

694
00:41:42,640 --> 00:41:45,520
Speaker 1: on an investigation and you want to check the Xbox

695
00:41:45,640 --> 00:41:50,200
Speaker 1: for any illegal information. It might not be readily apparent

696
00:41:50,640 --> 00:41:53,160
Speaker 1: that such information is on that Xbox if you don't

697
00:41:53,200 --> 00:41:55,719
Speaker 1: know where to look, and you can't easily scan it

698
00:41:55,960 --> 00:41:59,640
Speaker 1: with most forensic software. So digital forensics experts developed a

699
00:41:59,680 --> 00:42:01,760
Speaker 1: tool called the x f T, which is a command

700
00:42:01,880 --> 00:42:05,040
Speaker 1: line utility. It behaves like a Linux shell and allows

701
00:42:05,080 --> 00:42:08,120
Speaker 1: an investigator to image the file system of an Xbox,

702
00:42:08,440 --> 00:42:11,279
Speaker 1: which then would allow an analyst to browse the contents

703
00:42:11,520 --> 00:42:14,480
Speaker 1: on the game console in the search for illegal material.

704
00:42:14,800 --> 00:42:18,879
Speaker 1: And it can record a browse session so that prosecutors

705
00:42:18,960 --> 00:42:22,399
Speaker 1: could present that to jurors in a trial to show

706
00:42:22,440 --> 00:42:26,279
Speaker 1: exactly where a criminal hid data on the game system. Now,

707
00:42:26,360 --> 00:42:28,760
Speaker 1: one forensic tool I think is really neat is actually

708
00:42:28,800 --> 00:42:31,040
Speaker 1: not high tech at all. It's actually pretty low tech.

709
00:42:31,120 --> 00:42:33,080
Speaker 1: But that's kind of why I like it. It's so elegant,

710
00:42:33,640 --> 00:42:38,440
Speaker 1: and it's the use of magnetic fingerprint powder and magnetic wands.

711
00:42:38,800 --> 00:42:42,280
Speaker 1: Sounds very hairy potter ish, but it's not the powder.

712
00:42:42,480 --> 00:42:44,719
Speaker 1: The magnetic powder. It's dark. It can be used as

713
00:42:44,800 --> 00:42:46,920
Speaker 1: you know dark powder, black powder that you would typically

714
00:42:47,000 --> 00:42:50,040
Speaker 1: use when dusting for prints, but this particular powder contains

715
00:42:50,120 --> 00:42:54,120
Speaker 1: iron filings in it, which means it's attracted to magnets.

716
00:42:54,640 --> 00:42:56,960
Speaker 1: So when you want to dust a surface for prints,

717
00:42:57,520 --> 00:42:59,960
Speaker 1: you take out the magnetic wand. Now this is essentially

718
00:43:00,040 --> 00:43:03,880
Speaker 1: a plastic cylinder, and there's a cap on one end

719
00:43:03,920 --> 00:43:06,560
Speaker 1: of this plastic cylinder. It's got an end on a

720
00:43:06,680 --> 00:43:10,560
Speaker 1: capped end. Inside the cylinder is a magnet that's on

721
00:43:10,640 --> 00:43:13,360
Speaker 1: the end of a plunger. So if you push the

722
00:43:13,400 --> 00:43:16,000
Speaker 1: plunger all the way down, the magnet is pressed up

723
00:43:16,080 --> 00:43:19,400
Speaker 1: against the back end of that cap, the inside of

724
00:43:19,560 --> 00:43:22,080
Speaker 1: the cap. Then you can use the wand to pick

725
00:43:22,160 --> 00:43:24,520
Speaker 1: up the magnetic powder and it's going to clump to

726
00:43:24,640 --> 00:43:28,040
Speaker 1: the end of the wand you would then gently move

727
00:43:28,160 --> 00:43:32,560
Speaker 1: the wand across the surface that you are dusting for prints,

728
00:43:33,040 --> 00:43:35,280
Speaker 1: and you would use it like it's a brush, except

729
00:43:35,320 --> 00:43:37,319
Speaker 1: instead of it being the bristles of a brush, it's

730
00:43:37,360 --> 00:43:40,600
Speaker 1: actually the magnetic powder itself. And you're not letting the

731
00:43:40,680 --> 00:43:43,799
Speaker 1: wand contact the paper, it's just the powder. So as

732
00:43:43,840 --> 00:43:46,600
Speaker 1: you do this, some of the magnetic powder comes loose,

733
00:43:46,840 --> 00:43:49,120
Speaker 1: and if their fingerprints on the surface, the powder will

734
00:43:49,280 --> 00:43:52,840
Speaker 1: reveal the presence of those fingerprints. Once you're done brushing

735
00:43:52,920 --> 00:43:55,919
Speaker 1: the surface, you can then move the wand back over

736
00:43:56,120 --> 00:43:59,399
Speaker 1: to the container of magnetic powder. You position the wand

737
00:43:59,440 --> 00:44:01,239
Speaker 1: over the contain inner so that you're being nice and

738
00:44:01,280 --> 00:44:04,399
Speaker 1: careful and neat, and then you pull the plunger back

739
00:44:04,640 --> 00:44:07,400
Speaker 1: up the length of the cylinder. This moves the magnet

740
00:44:07,520 --> 00:44:11,120
Speaker 1: away from that capped end, and the magnetic powder will

741
00:44:11,200 --> 00:44:14,279
Speaker 1: just fall freely down into the container because there's no

742
00:44:14,440 --> 00:44:17,080
Speaker 1: longer that they're no longer close enough to the magnetic

743
00:44:17,200 --> 00:44:21,160
Speaker 1: field to be attracted to it anymore. One thing that

744
00:44:21,280 --> 00:44:22,920
Speaker 1: you do have to take into account if you're using

745
00:44:22,920 --> 00:44:26,080
Speaker 1: this stuff is it is more abrasive than normal black powder,

746
00:44:26,200 --> 00:44:29,040
Speaker 1: so brushing has to be very gentle. As for future

747
00:44:29,080 --> 00:44:33,120
Speaker 1: technologies and forensics, we might see investigators look at stuff

748
00:44:33,160 --> 00:44:36,759
Speaker 1: like the microbiomes we carry with us, those those or

749
00:44:36,960 --> 00:44:40,040
Speaker 1: those kind of cultures of micro organisms that are unique

750
00:44:40,160 --> 00:44:43,840
Speaker 1: to us. No two people have the same microbiomes, although

751
00:44:44,280 --> 00:44:49,160
Speaker 1: sexual contact can intermingle the microbiomes of one person and another.

752
00:44:49,239 --> 00:44:54,319
Speaker 1: In fact, an investigation could reveal that. So say it's

753
00:44:54,360 --> 00:44:57,320
Speaker 1: a it's a case where someone is coming forward and

754
00:44:57,480 --> 00:45:02,359
Speaker 1: they have an accusation and in volves sexual assault, then

755
00:45:02,760 --> 00:45:05,560
Speaker 1: investigation of the microbiome might be one of the ways

756
00:45:05,760 --> 00:45:09,880
Speaker 1: you could confirm that uh it. So being able to

757
00:45:09,960 --> 00:45:13,880
Speaker 1: identify and classify microbioms could become a really important investigative

758
00:45:13,960 --> 00:45:16,520
Speaker 1: tool in cases where you may not have a good

759
00:45:16,640 --> 00:45:19,680
Speaker 1: DNA sample to work with. UH. For that to happen,

760
00:45:20,320 --> 00:45:24,000
Speaker 1: that scientists have to prove that it's a reliable way

761
00:45:24,280 --> 00:45:28,680
Speaker 1: of identifying a person. UH that they have to show

762
00:45:28,840 --> 00:45:32,479
Speaker 1: that it is in fact something that you could base

763
00:45:32,600 --> 00:45:35,360
Speaker 1: a legal case on and it's so they have to

764
00:45:35,440 --> 00:45:40,480
Speaker 1: show that it's it's a verifiable and reliable technology. Another

765
00:45:40,600 --> 00:45:43,719
Speaker 1: line of investigation might focus on pollen particles that can

766
00:45:43,760 --> 00:45:46,719
Speaker 1: indicate specific travel patterns people have taken based upon the

767
00:45:46,840 --> 00:45:49,320
Speaker 1: pollen they've come in contact with and they have on

768
00:45:49,400 --> 00:45:52,480
Speaker 1: their clothes or skin. The study of pollen is called

769
00:45:52,960 --> 00:45:57,120
Speaker 1: palein ology p A L Y N O L O

770
00:45:57,280 --> 00:45:59,680
Speaker 1: g Y. It's pretty hefty stuff because there are a

771
00:45:59,760 --> 00:46:02,440
Speaker 1: hun ords of thousands of species of flowering plants out there,

772
00:46:02,920 --> 00:46:07,440
Speaker 1: so it is not easy to identify pollen UH necessarily,

773
00:46:07,560 --> 00:46:10,040
Speaker 1: but it could be a promising addition to the forensic

774
00:46:10,120 --> 00:46:13,960
Speaker 1: investigators growing collection of tools and strategies. And there's other

775
00:46:14,000 --> 00:46:16,399
Speaker 1: stuff that didn't talk about. I mean, there's stuff where

776
00:46:16,440 --> 00:46:20,719
Speaker 1: you could look at the computer system on a car

777
00:46:21,040 --> 00:46:25,160
Speaker 1: to look for uh, indications of things that you might

778
00:46:25,280 --> 00:46:29,480
Speaker 1: suspect based upon a crime that might have been committed

779
00:46:29,560 --> 00:46:33,759
Speaker 1: by someone driving. There's a lot of different avenues of

780
00:46:33,880 --> 00:46:37,680
Speaker 1: investigation out there, and honestly, I could do a full

781
00:46:37,920 --> 00:46:41,240
Speaker 1: podcast series about these, but I thought it was interesting

782
00:46:41,320 --> 00:46:43,799
Speaker 1: to kind of give this this look into what's being

783
00:46:43,960 --> 00:46:47,280
Speaker 1: used today and the technologies that might be used tomorrow.

784
00:46:47,880 --> 00:46:50,160
Speaker 1: Uh So thanks a lot Hakim who asked us to

785
00:46:50,640 --> 00:46:52,800
Speaker 1: look into this, I greatly appreciate it. If you have

786
00:46:52,840 --> 00:46:55,920
Speaker 1: a suggestion for a future episodes tech stuff, why not,

787
00:46:56,200 --> 00:46:58,839
Speaker 1: right and let me know what that is. The addresses

788
00:46:58,920 --> 00:47:01,600
Speaker 1: tech Stuff at how stuff works dot com. You can

789
00:47:01,680 --> 00:47:03,560
Speaker 1: drop me a line on Facebook or Twitter. The handle

790
00:47:03,600 --> 00:47:06,120
Speaker 1: at both of those is tech stuff. H s W.

791
00:47:06,640 --> 00:47:08,839
Speaker 1: Don't forget to go over to t public dot com

792
00:47:08,960 --> 00:47:11,439
Speaker 1: slash tech stuff to get all your tech stuff merch.

793
00:47:12,080 --> 00:47:16,000
Speaker 1: That's t e public dot com slash tech Stuff. I

794
00:47:16,200 --> 00:47:20,080
Speaker 1: personally still love the Ada Lovelace design so much. I'm

795
00:47:20,320 --> 00:47:22,919
Speaker 1: getting a T shirt with that on it as soon

796
00:47:23,040 --> 00:47:25,040
Speaker 1: as I possibly can. I've actually got the order in

797
00:47:25,160 --> 00:47:27,239
Speaker 1: I'm just waiting for it to get to me. But

798
00:47:27,480 --> 00:47:30,920
Speaker 1: you may see something you really love and you, you know, purchase.

799
00:47:31,000 --> 00:47:33,600
Speaker 1: Your purchase can support our show. We greatly appreciate it.

800
00:47:34,440 --> 00:47:37,480
Speaker 1: Don't forget to follow us on Instagram and I'll talk

801
00:47:37,480 --> 00:47:45,960
Speaker 1: to you again really soon. For more on this and

802
00:47:46,080 --> 00:47:48,600
Speaker 1: thousands of other topics. Is it how stuff works dot

803
00:47:48,640 --> 00:47:48,839
Speaker 1: com