WEBVTT - TechStuff Investigates Forensic Technology 0:00:04.120 --> 0:00:07.160 Get in touch with technology with tech Stuff from how 0:00:07.200 --> 0:00:13.800 stuff Works dot com. Hey there, and welcome to tech Stuff. 0:00:13.840 --> 0:00:16.400 I am your host, Jonathan Strickland. I'm an executive producer 0:00:16.440 --> 0:00:18.959 with how Stuff Works in I love all things tech, 0:00:19.400 --> 0:00:22.560 though today we're gonna be talking about a branch of 0:00:22.600 --> 0:00:26.560 technology that gets up. I'm pretty grim and pretty serious. Uh, 0:00:26.600 --> 0:00:29.319 this is a listener request. Listener Hakim asked that I 0:00:29.400 --> 0:00:32.520 do an episode about forensic technology, so I'm actually gonna 0:00:32.520 --> 0:00:37.000 do a pair of episodes. It is fascinating stuff and 0:00:37.040 --> 0:00:39.440 it's definitely not quite the same as what we see 0:00:39.680 --> 0:00:43.360 in depictions on film or in television shows. That's not 0:00:43.440 --> 0:00:47.120 a big surprise. We've covered multiple times how technology in 0:00:47.200 --> 0:00:50.120 pop culture is very different from what we see in reality. 0:00:50.320 --> 0:00:53.320 But in this episode, I'm going to specifically focus on 0:00:53.400 --> 0:00:56.920 the history of forensics, and in the next episode we'll 0:00:56.920 --> 0:00:59.320 talk about some of the cutting edge technologies that are 0:00:59.400 --> 0:01:03.560 used in for psick investigations today. So forensics, first of all, 0:01:03.600 --> 0:01:07.080 has a few different definitions. If you are being very literal, 0:01:07.200 --> 0:01:10.200 it can mean debate or discussion in Latin, but as 0:01:10.240 --> 0:01:12.560 we tend to use it today, we refer to it 0:01:12.680 --> 0:01:16.480 as the science with regard to detecting and solving crimes. 0:01:16.880 --> 0:01:20.000 So not just if a crime has occurred, but how 0:01:20.040 --> 0:01:22.919 did a crime occur, how did it unfold in time, 0:01:23.160 --> 0:01:26.679 who was involved? That sort of stuff. And like all sciences, 0:01:26.880 --> 0:01:30.080 forensics can trace its history back far before the formal 0:01:30.200 --> 0:01:34.440 codification of the scientific method, and this involves lots of 0:01:34.480 --> 0:01:39.280 different ideas and processes for different elements of investigation developing 0:01:39.280 --> 0:01:43.520 at various times throughout history. Like most things, forensics involved 0:01:43.640 --> 0:01:49.000 a lot of different ideas being tested throughout centuries before 0:01:49.040 --> 0:01:51.840 maturing as a collection of practices. So one of the 0:01:51.880 --> 0:01:54.160 easy ideas we can talk about, because there are a 0:01:54.200 --> 0:01:59.160 lot of different independent threads that converge to become forensics. 0:02:00.040 --> 0:02:04.120 On easy entry point is a discussion about fingerprints and 0:02:04.200 --> 0:02:07.520 developing the skills and technology to detect and identify them 0:02:07.560 --> 0:02:11.360 and classify them in the context of criminal investigations. Now, 0:02:11.400 --> 0:02:14.359 I've done a full episode on fingerprinting in the past, 0:02:14.800 --> 0:02:17.800 so I'll give more of a short overview of the 0:02:17.800 --> 0:02:21.800 whole thing here. There are records that actually indicate that 0:02:21.960 --> 0:02:26.639 handprints were used as evidence and investigations for burglary back 0:02:26.680 --> 0:02:30.160 in China more than two thousand years ago, and the 0:02:30.200 --> 0:02:34.000 book with the English title Universal History, which was published 0:02:34.000 --> 0:02:36.960 in Persia in the th hundreds, mentioned the practice of 0:02:37.000 --> 0:02:43.000 identifying people based upon their fingerprints. European anatomists and philosophers 0:02:43.000 --> 0:02:47.120 made observations about fingerprints in the seventeenth century, but those 0:02:47.160 --> 0:02:51.120 observations weren't really connected to the idea that fingerprints themselves 0:02:51.120 --> 0:02:53.880 are unique to specific individuals and that no two people 0:02:53.919 --> 0:02:58.320 would share the same ones. J. C. A. Meyer, a 0:02:58.440 --> 0:03:03.919 German anatomist, published Anatomical Copper Plates with Appropriate Explanations. That's 0:03:03.919 --> 0:03:06.320 the actual title of the book, Anatomical Copper Plates with 0:03:06.360 --> 0:03:11.040 Appropriate Explanations, in sounds like it was a rip roaring 0:03:11.160 --> 0:03:15.080 picture book anyway. He described fingerprints as being unique, but 0:03:15.200 --> 0:03:18.600 also noted that they can appear similar to one another. So, 0:03:18.639 --> 0:03:21.840 in other words, on close examination you will see that 0:03:21.919 --> 0:03:24.760 they are unique, but on casual glance you may not 0:03:24.840 --> 0:03:28.320 be able to make that distinction easily. The nineteenth century 0:03:28.360 --> 0:03:30.840 saw a lot more work to define the qualities of 0:03:30.880 --> 0:03:34.359 fingerprints and how to classify them. How would you describe 0:03:34.720 --> 0:03:37.160 the fingerprints, how would you describe the grooves in such 0:03:37.200 --> 0:03:39.240 a way that it made sense? And then how would 0:03:39.240 --> 0:03:42.800 you classify fingerprints so that you could kind of categorize them, 0:03:43.080 --> 0:03:45.640 and how would you preserve impressions of them. All of 0:03:45.680 --> 0:03:49.880 these were ideas and practices that were developed in the 0:03:49.920 --> 0:03:54.080 eighteen hundreds. By the end of that century, Mark Twain 0:03:54.320 --> 0:03:57.760 was incorporating the idea of using fingerprints to identify a 0:03:57.880 --> 0:04:00.840 murderer and a couple of his books, And right at 0:04:00.880 --> 0:04:04.960 the cusp of the twentieth century, just before nineteen hundred, 0:04:05.040 --> 0:04:08.400 you had organizations starting to build out fingerprint files for 0:04:08.480 --> 0:04:12.160 the purposes of identifications. So the idea of using fingerprints 0:04:12.200 --> 0:04:16.120 to uh to ascertain the identity of someone you know 0:04:16.120 --> 0:04:19.320 they've left a fingerprint behind a scene, that had really 0:04:19.360 --> 0:04:23.880 started to take hold by the late nineteenth century, says 0:04:23.960 --> 0:04:28.279 the Sherlock Holmes era. The twentieth century saw a rapid 0:04:28.360 --> 0:04:32.599 development of technology in all different fields. Right, we see 0:04:32.600 --> 0:04:36.039 in the nineteen hundreds crazy amounts of innovation in all 0:04:36.080 --> 0:04:41.360 sorts of industries. But that included eventually things like digitizing 0:04:41.440 --> 0:04:45.320 records of fingerprint files, which would allow law enforcement to 0:04:45.360 --> 0:04:49.240 create the automated fingerprint identification system. And now in the 0:04:49.320 --> 0:04:53.120 United States, the Department of Homeland Security oversees a database 0:04:53.160 --> 0:04:57.760 containing more than one twenty million people's fingerprints. The FBI 0:04:57.839 --> 0:05:01.640 conducts more than three hundred thousand KORD searches per day 0:05:01.680 --> 0:05:06.160 against more than one forty million computerized fingerprint records. Uh 0:05:06.279 --> 0:05:07.960 some of those are criminals, some of those are civil, 0:05:08.560 --> 0:05:13.120 and so like civil fingerprints, you might have to submit 0:05:13.200 --> 0:05:17.120 for fingerprinting at when getting a a an i D 0:05:17.520 --> 0:05:19.280 like a state issued i D for example in the 0:05:19.360 --> 0:05:24.919 United States. The world's largest database of fingerprint information, not 0:05:25.000 --> 0:05:29.520 just fingerprint but biometric in general, actually belongs to a 0:05:29.560 --> 0:05:34.200 company called the Unique Identification Authority of India. It's really 0:05:34.200 --> 0:05:36.440 more of an organization, I guess I should say so 0:05:36.520 --> 0:05:40.640 that also includes face and biometric records and the goal 0:05:40.760 --> 0:05:45.240 to provide all one point to five billion residents of 0:05:45.279 --> 0:05:48.359 India with the option to record their biometric data for 0:05:48.360 --> 0:05:53.120 the purposes of providing reliable national i D documents. Participation 0:05:53.120 --> 0:05:56.480 in that database, by the way, is voluntary, so they 0:05:56.480 --> 0:06:01.359 aren't forced to submit to this uh In the citizens 0:06:01.360 --> 0:06:05.279 of India can opt into this system for the purposes 0:06:05.360 --> 0:06:08.160 of making it easier to get these kinds of national ideas. 0:06:09.120 --> 0:06:13.159 So that's the idea behind fingerprinting. This this concept of 0:06:13.200 --> 0:06:15.120 being able to look at the loops in the worlds 0:06:15.160 --> 0:06:18.680 and the various ridges and to compare them against a 0:06:18.720 --> 0:06:21.680 large database to see if there's a match. There were 0:06:21.760 --> 0:06:23.440 very familiar with that, and like I said, I did 0:06:23.440 --> 0:06:26.559 a full episode. So if you want to learn way 0:06:26.600 --> 0:06:31.600 more about the process of fingerprinting and identification through fingerprinting, 0:06:31.920 --> 0:06:34.680 go through the text of archives. There's an episode just 0:06:34.800 --> 0:06:39.040 about that. So let's move over to ballistics. Now, technically, 0:06:39.839 --> 0:06:44.000 ballistics is the science of projectiles and firearms. Within the 0:06:44.040 --> 0:06:48.360 context of forensics. We tend to use the term ballistics 0:06:48.440 --> 0:06:51.280 to talk about the various aspects of an investigation into 0:06:51.279 --> 0:06:54.720 a crime that included a gun being fired at least once, 0:06:55.160 --> 0:06:58.200 and a lot can go into that. One person I 0:06:58.240 --> 0:07:02.120 need to mention is a guy named Henry Goddard, and 0:07:02.200 --> 0:07:04.480 there actually were a couple of Henry Goddard's, So I'm 0:07:04.520 --> 0:07:08.400 not talking about the American psychologist who advocated for intelligence 0:07:08.400 --> 0:07:12.080 testing in the early twentieth century. I'm instead talking about 0:07:12.120 --> 0:07:16.520 a nineteenth century member of London's Bow Street Runners. And 0:07:16.600 --> 0:07:19.160 holy cow, this is a group that needs coverage in 0:07:19.200 --> 0:07:22.960 a show like Ridiculous History, not because it's ridiculous, but 0:07:23.040 --> 0:07:26.120 because it is fascinating. This is one of those things 0:07:26.160 --> 0:07:28.840 where I had heard about the Bow Street runners, but 0:07:28.920 --> 0:07:31.320 I hadn't really looked into it. And by the way, 0:07:31.560 --> 0:07:33.920 if someone comes in to tell me that no, it's 0:07:33.920 --> 0:07:36.560 Bow Street in London and Bow Street not Bow Street, 0:07:37.080 --> 0:07:41.000 I apologize. That's my American ignorance showing through. I'm gonna 0:07:41.040 --> 0:07:43.280 go with Bow Street because that's just how I assumed 0:07:43.320 --> 0:07:46.040 it was pronounced, but I fully admit it could be wrong. 0:07:46.120 --> 0:07:50.400 So quick history lesson. Leading up to the late seventeen hundreds, 0:07:50.800 --> 0:07:53.520 it was customary in London that if you happen to 0:07:53.520 --> 0:07:56.360 be a man, you were expected to participate in the 0:07:56.400 --> 0:07:59.320 policing of your own community. So if you saw a 0:07:59.320 --> 0:08:02.800 crime being commit did you were expected to intervene in 0:08:02.800 --> 0:08:08.280 that crime and apprehend the perpetrator and convict that person. 0:08:08.880 --> 0:08:11.480 You were also expected to send serve time in the 0:08:11.640 --> 0:08:15.960 night watch, which meant that between the hours of say 0:08:16.120 --> 0:08:19.760 eight or nine PM and dawn, you would have to 0:08:19.800 --> 0:08:23.040 patrol streets and make sure that that there were no 0:08:23.120 --> 0:08:27.880 suspicious people lurking about, or that if anyone was seen 0:08:27.960 --> 0:08:29.760 on the streets, that they had a valid reason to 0:08:29.800 --> 0:08:32.679 be out there and they weren't up to no good. 0:08:33.480 --> 0:08:35.520 And a lot of people were starting to get a 0:08:35.520 --> 0:08:38.280 little nervous about this because by the seventeen hundreds you 0:08:38.320 --> 0:08:41.640 had a new class that had formed in London. And 0:08:41.640 --> 0:08:46.319 previously you had the commoners and you had the nobility, 0:08:46.640 --> 0:08:50.600 and that was the way of things in the in 0:08:50.720 --> 0:08:55.120 England for quite some time. Uh and then by the 0:08:55.160 --> 0:08:57.520 Renaissance you were starting to see the rise of the 0:08:57.559 --> 0:09:00.559 middle class, and by the seventeen hundreds you the upper 0:09:00.600 --> 0:09:04.000 middle class. You had people who were wealthy. They weren't noble, 0:09:04.280 --> 0:09:06.560 but they owned a lot of wealth, whereas you had 0:09:06.640 --> 0:09:10.000 nobility that were they had noble titles, but some of 0:09:10.000 --> 0:09:13.439 them weren't very wealthy at all. So this really created 0:09:13.480 --> 0:09:18.160 confusion in England, where for the longest time social status 0:09:18.240 --> 0:09:22.160 was based upon nobility, and nobility tended to bring wealth 0:09:22.240 --> 0:09:25.960 along with it. Anyway, you had these upper class folks 0:09:25.960 --> 0:09:29.560 in London, men who were not terribly keen on the 0:09:29.640 --> 0:09:33.520 idea of having to patrol their city streets and getting 0:09:33.559 --> 0:09:37.600 involved in altercations that could involve violent criminals. You think, 0:09:37.720 --> 0:09:40.839 I didn't work so hard to become so successful to 0:09:41.720 --> 0:09:46.960 potentially get my skull caved in by a villain with 0:09:47.000 --> 0:09:49.520 a club. So I'm going to hire someone to go 0:09:49.600 --> 0:09:53.960 in my place, and people started to hire deputies. Well. 0:09:53.960 --> 0:09:57.120 Around the same time, royal proclamations had created a reward 0:09:57.280 --> 0:10:00.560 system for people who helped keep the peace by convicting 0:10:00.559 --> 0:10:06.120 criminals of various crimes, including various thefts, so this gave 0:10:06.240 --> 0:10:10.840 rise to an unofficial occupation called thief taker. Thief takers 0:10:10.840 --> 0:10:14.800 would often not just make money by pursuing convictions of criminals, 0:10:14.840 --> 0:10:18.600 but also essentially selling back stolen property to the rightful owners. 0:10:18.720 --> 0:10:23.080 So they would get money by putting the thief behind 0:10:23.120 --> 0:10:25.680 bars and get more money by selling the stolen property 0:10:25.720 --> 0:10:27.480 back to the person who owned in the first place. 0:10:28.480 --> 0:10:32.920 So then you had Henry and John Fielding and they 0:10:32.960 --> 0:10:36.280 had a house on Bow Street. Henry Fielding started to 0:10:36.320 --> 0:10:40.120 pay retainers to men who were either constables or ex 0:10:40.200 --> 0:10:45.560 constables to locate and arrest criminals, particularly violent criminals, and 0:10:45.559 --> 0:10:48.000 if you did that, you were entitled to the reward. 0:10:48.320 --> 0:10:49.840 So if you were one of the members of the 0:10:49.840 --> 0:10:53.200 Bow Street Runners and you apprehended someone, you convicted that 0:10:53.280 --> 0:10:55.840 person of a crime, you would get the reward there 0:10:56.080 --> 0:10:57.960 and the Fieldings hope that what they could do is 0:10:58.000 --> 0:11:01.280 managed this group and rain in any corruption to keep 0:11:01.320 --> 0:11:04.160 things on the level, and they essentially became a private 0:11:04.200 --> 0:11:08.320 police force of sorts, and over time they developed processes 0:11:08.320 --> 0:11:11.320 and procedures that would become the foundation of modern policing 0:11:11.320 --> 0:11:15.520 in many ways. Now, Goddard, who had mentioned before, was 0:11:15.559 --> 0:11:18.640 one of these bow street runners or policemen, and he 0:11:18.720 --> 0:11:22.160 identified a murderer in eighteen thirty five by linking a 0:11:22.200 --> 0:11:25.640 bullet recovered from a victim to the person who made 0:11:25.840 --> 0:11:28.959 the bullet, because in those days most people who owned 0:11:29.040 --> 0:11:34.040 guns made their own bullets. You did this by pouring 0:11:34.120 --> 0:11:37.520 molten lead into a two piece mold, to set it 0:11:37.760 --> 0:11:41.040 into that mold, and then you would, you know, forge 0:11:41.080 --> 0:11:44.600 a bullet. Goddard saw in the bullet, and imperfection that 0:11:44.679 --> 0:11:47.960 he reasoned was from the manufacturing process, which meant the 0:11:48.040 --> 0:11:50.920 mold itself would have evidence of that fault, and if 0:11:50.920 --> 0:11:53.480 you were to mold another bullet with that mold, you 0:11:53.480 --> 0:11:56.040 should be able to replicate the fault in it. So 0:11:56.120 --> 0:11:58.840 Goddard was able to get a confession from the suspect 0:11:59.160 --> 0:12:01.480 and one to convict action. It was only later that 0:12:01.480 --> 0:12:04.800 people pointed out his approach was not necessarily the most scientific, 0:12:04.920 --> 0:12:08.320 as similar molds could have produced a similar looking bullet. 0:12:08.720 --> 0:12:11.200 But it was an early example of ballistics and forensics. 0:12:11.200 --> 0:12:14.520 It's just it wasn't a terribly scientifically solid one. But 0:12:14.600 --> 0:12:16.960 you flash forward a century later and then you have 0:12:17.360 --> 0:12:21.040 Calvin Goddard, but no relation to Henry Goddard, whom I 0:12:21.120 --> 0:12:24.719 just talked about. Calvin Goddard was a scientist, a researcher, 0:12:24.720 --> 0:12:28.120 and a military officer, and in nineteen five he wrote 0:12:28.120 --> 0:12:31.960 an article titled Forensic Ballistics and described using a special 0:12:32.000 --> 0:12:36.400 type of microscope he had created called a comparison microscope 0:12:36.400 --> 0:12:40.280 when examining side by side specimens. Now, essentially a comparison 0:12:40.320 --> 0:12:44.720 microscope is too light. Microscopes connected by an optical bridge. 0:12:45.240 --> 0:12:49.880 So there are two uh ocular lenses, two eye pieces, 0:12:50.280 --> 0:12:52.480 so you look in one with each giant. It looks 0:12:52.520 --> 0:12:56.160 almost like binoculars, excepted some microscope. And it meant that 0:12:56.200 --> 0:12:58.440 you could put a sample under one and a sample 0:12:58.520 --> 0:13:00.840 under the second one, and pair of the two in 0:13:00.880 --> 0:13:03.520 a single view. And he used it to compare bullet 0:13:03.559 --> 0:13:07.160 casings or bullet shells and bullets recovered from crime scenes, 0:13:07.679 --> 0:13:10.080 and by being able to see both a bullet and 0:13:10.120 --> 0:13:12.760 it's casing, he could verify whether or not the bullet 0:13:13.120 --> 0:13:16.640 actually belonged to that casing by the markings. He could 0:13:16.679 --> 0:13:21.880 also if say you had recovered a firearm from a 0:13:21.920 --> 0:13:25.640 suspect and you were wondering if it was the same 0:13:25.760 --> 0:13:28.240 firearm as the one used in a crime, you could 0:13:28.280 --> 0:13:32.080 fire that into a soft target, retrieved the bullets, compare 0:13:32.080 --> 0:13:36.280 them side by side, so uh that would allow you 0:13:36.360 --> 0:13:39.200 to look at them in real time next to each 0:13:39.200 --> 0:13:42.320 other at a microscopic level. Previously, what you would have 0:13:42.360 --> 0:13:45.440 to do is look at one like the actual one 0:13:45.480 --> 0:13:47.960 that was found at the scene of a crime, and 0:13:48.280 --> 0:13:52.720 make note of any indentations or markings on the bullet, 0:13:53.040 --> 0:13:55.520 and then you would look at a second one separately. 0:13:55.840 --> 0:13:57.880 But that men, you had to rely upon your memory 0:13:57.960 --> 0:14:01.240 in part to make this comparison in and memories are faulty, 0:14:01.440 --> 0:14:04.320 so his technology would end up playing a vital role 0:14:04.400 --> 0:14:08.960 in several early twentieth century investigations, including the investigation into 0:14:08.960 --> 0:14:13.160 the infamous St. Valentine's Day massacre. Goddard was able to 0:14:13.200 --> 0:14:15.480 prove that the bullets that were fired in that crime 0:14:15.880 --> 0:14:18.680 did not come from police guns because the men who 0:14:18.679 --> 0:14:22.240 committed the murders were wearing Chicago police uniforms when they 0:14:22.240 --> 0:14:24.880 did it, but they said, well, no, these didn't come 0:14:24.880 --> 0:14:27.960 from the guns that belonged to police officers. Later on 0:14:28.040 --> 0:14:31.280 they were able to discover a gun that belonged to 0:14:31.320 --> 0:14:35.720 a mobster that did match the bullets that were fired 0:14:35.760 --> 0:14:38.000 during the St. Valentine's Day masacre. So it was one 0:14:38.120 --> 0:14:42.280 of the guns used in that terrible, terrible event. They 0:14:42.320 --> 0:14:44.840 were figured out it wasn't vigilante justice at all, it 0:14:44.920 --> 0:14:48.000 was a mob hit. Based upon the evidence, Godard would 0:14:48.040 --> 0:14:50.080 be asked to become the head of the first independent 0:14:50.120 --> 0:14:53.640 forensics science crime Lab, which was at Northwestern University in 0:14:53.760 --> 0:14:56.960 nineteen twenty nine. The lab later became known as the 0:14:57.040 --> 0:15:02.280 Scientific Crime Detection Laboratory of h AGO. Very influential lab. 0:15:02.760 --> 0:15:05.040 Now get a lot more to say about forensics science 0:15:05.040 --> 0:15:07.120 and its development over the years, but first let's take 0:15:07.160 --> 0:15:17.040 a quick break to thank our sponsor. One of the 0:15:17.120 --> 0:15:20.600 many things a ballistics expert in forensic studies would look 0:15:20.600 --> 0:15:22.720 at would be those marks left on a bullet after 0:15:22.760 --> 0:15:25.760 it has been fired from a gun. Modern guns have 0:15:26.000 --> 0:15:30.160 rifling in the barrels, which refers to grooves that are 0:15:30.200 --> 0:15:33.680 inside the barrel. They're meant to produce torque on a bullet, 0:15:33.880 --> 0:15:37.080 which forces the bullet to spin as it travels down 0:15:37.120 --> 0:15:40.040 the barrel, and it continues spinning when it emerges because 0:15:40.040 --> 0:15:42.960 a spinning projectile has a much more stable flight path 0:15:43.360 --> 0:15:46.520 due to behaving like a gyroscope. I talked about gyroscopes 0:15:46.560 --> 0:15:49.880 in recent episodes of tech Stuff. Essentially because of the 0:15:49.920 --> 0:15:53.760 conservation of angular momentum and objects spinning around an access 0:15:53.760 --> 0:15:58.200 of rotation resists changes in its orientation, so a spinning 0:15:58.240 --> 0:16:00.800 bullet will remain more true to its flight path. And 0:16:00.880 --> 0:16:04.120 a projectile fired from a smooth bore firearm which has 0:16:04.120 --> 0:16:06.600 no rifling on the inside of its gun barrel, but 0:16:06.720 --> 0:16:11.760 passing down this groove path essentially carves a pattern on 0:16:11.920 --> 0:16:14.760 a bullet. A bullets diameter is slightly larger than the 0:16:14.760 --> 0:16:17.520 board diameter of the barrel it is fired through. The 0:16:17.640 --> 0:16:21.400 bullet is of a softer material, so it will end 0:16:21.480 --> 0:16:24.600 up getting a pattern carved into it as it as 0:16:24.800 --> 0:16:27.600 as it's forced on this barrel at high velocity and 0:16:27.640 --> 0:16:31.000 begins to go into the spin. Investigators can actually count 0:16:31.000 --> 0:16:34.880 the number of grooves or impressions around the circumference of 0:16:34.880 --> 0:16:37.280 the bullet, and by looking down the length of a 0:16:37.320 --> 0:16:41.360 bullet from behind, the investigators can determine the twist direction 0:16:41.440 --> 0:16:44.320 of the rifling grooves inside the barrel, and this part 0:16:44.360 --> 0:16:48.040 of a gun barrel can wear down after use. That 0:16:48.120 --> 0:16:50.360 means that the patterns will end up being unique to 0:16:50.440 --> 0:16:53.160 specific guns. Even if you have two guns that are 0:16:53.200 --> 0:16:56.560 the same make and model, the wear pattern is going 0:16:56.560 --> 0:16:59.280 to be different for both of those so you will 0:16:59.400 --> 0:17:04.000 end up have different patterns actually imparted to the bullets 0:17:04.000 --> 0:17:07.399 fired out of those guns. So if investigators can retrieve 0:17:07.400 --> 0:17:09.959 bullets from a scene, they can potentially match those bullets 0:17:10.000 --> 0:17:13.119 to a specific firearm, assuming they also have possession of 0:17:13.119 --> 0:17:15.679 that firearm to compare the two, or they can use 0:17:15.720 --> 0:17:19.040 the patterns to potentially eliminate firearms that could not have 0:17:19.160 --> 0:17:22.159 produced those patterns. So, like I said before, the way 0:17:22.160 --> 0:17:25.880 you would typically do this is you have the suspect firearm, 0:17:25.960 --> 0:17:28.600 you fired it a few times, and you fire it 0:17:28.600 --> 0:17:31.520 into into a target that will preserve the integrity of 0:17:31.560 --> 0:17:33.959 the bullets. It's not designed to have the bullet break apart. 0:17:34.480 --> 0:17:36.000 So that way you have as good a sample as 0:17:36.000 --> 0:17:39.719 you possibly can. You compare the patterns on that bullet 0:17:39.840 --> 0:17:42.639 to the one that you have retrieved from the crime scene, 0:17:42.880 --> 0:17:44.679 and you look and see if they they are in 0:17:44.760 --> 0:17:47.840 fact similar enough to say they were both fired from 0:17:47.880 --> 0:17:52.800 the same weapon. Uh. Firearms also produced marks on cartridge cases, 0:17:52.960 --> 0:17:55.880 and no two firearms will do so exactly the same way. 0:17:55.960 --> 0:17:59.840 So cartridges will bear markings, they're different from rifling markings. 0:17:59.880 --> 0:18:03.400 They they might have something like a firing pin, Ambrussians, 0:18:03.600 --> 0:18:09.520 breach marks, extractor marks, and dejector marks. Depending upon the 0:18:09.520 --> 0:18:13.560 type of firearm you're talking about, surface characteristics created on 0:18:13.600 --> 0:18:16.600 the firearm itself from use will give it a uniqueness 0:18:16.960 --> 0:18:19.440 that other firearms won't reproduce. That's that where in Taro 0:18:19.560 --> 0:18:23.280 is telling you about um. But firearms also don't change 0:18:23.400 --> 0:18:26.359 super quickly, right. They do wear down over time, but 0:18:26.400 --> 0:18:29.359 it's not super super fast. Even if two are the 0:18:29.400 --> 0:18:32.520 same make and model, you're gonna have slight differences, like 0:18:32.560 --> 0:18:35.879 I said before, But they don't change so fast that 0:18:35.920 --> 0:18:39.000 you have to worry about identifying a gun. Well after 0:18:39.560 --> 0:18:42.640 a crime is committed, let's say that you have retrieved 0:18:42.640 --> 0:18:46.159 a bullet from the case of the crime scene, and 0:18:46.200 --> 0:18:48.440 let's say it's a cold case, like it's the case 0:18:48.520 --> 0:18:52.000 has gone cold and it's essentially shelved. And then later 0:18:52.040 --> 0:18:54.399 on you come across somebody and you're like I like 0:18:54.520 --> 0:18:57.080 this guy for that crime we never solved, you know, 0:18:57.160 --> 0:19:01.080 fifteen years ago, and this guy even had a gun 0:19:01.840 --> 0:19:04.600 that would have fired the bullets. It's the same style 0:19:04.640 --> 0:19:07.000 of gun that we suspect fired the bullets that we 0:19:07.000 --> 0:19:10.840 retrieved at that scene. Even though fifteen years have passed. 0:19:11.440 --> 0:19:14.960 You can fire that suspects gun and you can compare 0:19:15.000 --> 0:19:17.800 it against the bullet you retreat from the crime scene, 0:19:18.280 --> 0:19:20.960 and chances are there won't be so much wear and tear. 0:19:21.040 --> 0:19:23.080 Assuming it is the same gun, that you would be 0:19:23.119 --> 0:19:26.439 able to say, oh, it's the exact same firearm. So 0:19:26.520 --> 0:19:29.800 if you fire a gun once and you retreat the bullet, 0:19:30.000 --> 0:19:32.280 then you fire at ninety nine more times and you 0:19:32.400 --> 0:19:36.120 treat the one bullet, there should still be enough similarities 0:19:36.160 --> 0:19:38.600 between bullets one and one hundred for you to say 0:19:38.640 --> 0:19:41.199 they both definitely came from the same gun. In addition 0:19:41.200 --> 0:19:43.720 to studying bullets to determine if they were fired from 0:19:43.720 --> 0:19:47.760 a specific firearm, forensic investigators also examined bullet holes left 0:19:47.760 --> 0:19:50.439 it scenes to figure out where the person firing the 0:19:50.440 --> 0:19:53.840 gun was standing and how tall he or she was. 0:19:53.960 --> 0:19:56.480 Based on the evidence, the shape of a bullet hole 0:19:56.560 --> 0:20:00.080 gives us a lot of information. So some people might say, go, 0:20:00.200 --> 0:20:02.200 bullet holes are gonna be around, Well, that's not true 0:20:02.320 --> 0:20:06.680 unless the person firing the gun is firing at perfectly 0:20:06.800 --> 0:20:10.919 level at a ninety degree angle to whatever the surfaces 0:20:11.000 --> 0:20:13.920 that that ends up being hit by the bullet. Otherwise 0:20:13.920 --> 0:20:17.160 you're gonna get an elliptical shape from the bullet hole, 0:20:17.480 --> 0:20:19.720 and that elliptical shape will tell you a lot. It's 0:20:19.840 --> 0:20:22.000 it's angled, it will show that the bullet hit the 0:20:22.000 --> 0:20:25.360 wallet to bias. So you can determine the angle from 0:20:25.359 --> 0:20:27.439 which the bullet entered the wall, and if you have 0:20:27.440 --> 0:20:30.800 a suspect, you can use geometry to determine if that 0:20:30.920 --> 0:20:35.160 suspect could have been responsible. Not necessarily if they did 0:20:35.240 --> 0:20:37.240 or didn't do it, but you can at least say, well, 0:20:37.400 --> 0:20:40.000 is it possible that they did it. This is where 0:20:40.000 --> 0:20:42.399 you look at, say, bullet holes in the wall. You 0:20:42.480 --> 0:20:45.480 determine the angle from where the bullet entered the wall. 0:20:45.520 --> 0:20:48.639 You've figured out where what distance from the wall the 0:20:48.640 --> 0:20:51.480 shooter was, and you say, well, if the shooter was 0:20:51.600 --> 0:20:54.400 five ft ten, this makes sense. But if you start 0:20:54.440 --> 0:20:58.320 getting too short or too tall from that, then it wouldn't. 0:20:58.520 --> 0:21:01.399 The angle doesn't make any that's based upon what we know. 0:21:01.960 --> 0:21:04.680 So let's say that you've got a four ft three 0:21:04.720 --> 0:21:07.600 inch tall suspect. You might say, well, there's no way 0:21:08.000 --> 0:21:11.119 this person is too short for that to have worked 0:21:11.160 --> 0:21:14.440 out the way we believe it did. So that those 0:21:14.480 --> 0:21:18.080 bullet holes can tell you a lot of information, but 0:21:18.200 --> 0:21:20.160 you have to use geometry in order to do it, 0:21:21.240 --> 0:21:23.639 which means I would be really bad at it. I 0:21:23.680 --> 0:21:27.160 was terrible at geometry. It's great at trigonometry, but not 0:21:27.240 --> 0:21:31.719 so much at geometry. Anyway, these days, investigators may use 0:21:31.760 --> 0:21:35.840 advanced technologies like laser scanners to get really precise information 0:21:35.880 --> 0:21:39.600 from a crime scene in order to create a simulation 0:21:39.720 --> 0:21:43.960 to to view things like the angle of fire and 0:21:44.000 --> 0:21:46.280 the distance and that sort of stuff. I'll talk more 0:21:46.320 --> 0:21:50.000 about that in the next episode. However, other science and 0:21:50.080 --> 0:21:52.399 technology that relates to crimes in which a gun was 0:21:52.440 --> 0:21:56.560 fired might include detecting residue from gunshots. By the nineteen seventies, 0:21:56.720 --> 0:22:00.680 scientists started using scanning electron microscopes to do at I 0:22:00.720 --> 0:22:04.160 also talk about scanning electron microscopes in the next episode 0:22:04.160 --> 0:22:06.719 and talk about how those work. It's pretty fascinating stuff. 0:22:07.240 --> 0:22:11.800 But forensics goes beyond fingerprints and ballistics in the eighteen thirties, 0:22:12.119 --> 0:22:15.280 there was a chemist named James Marsh who developed a 0:22:15.359 --> 0:22:18.080 chemical test we called the Marsh test and it was 0:22:18.119 --> 0:22:21.840 specifically to detect the presence of arsenic and he developed 0:22:21.840 --> 0:22:25.879 the test after he determined the prevailing methodology was inferior 0:22:26.000 --> 0:22:32.520 after a pretty upsetting incident in his life and all 0:22:32.600 --> 0:22:35.760 had to do with a murder trial. In two there 0:22:35.800 --> 0:22:38.280 was a man who stood accused of having murdered his 0:22:38.400 --> 0:22:42.879 grandfather by poisoning his granddad's coffee with arsenic and James 0:22:42.960 --> 0:22:47.040 Marsh was called upon to do an investigation and present 0:22:47.160 --> 0:22:50.040 his findings to court, and he was meant to test 0:22:50.160 --> 0:22:53.440 the coffee for arsenic. Now, the standard at the time 0:22:53.920 --> 0:22:58.800 was that you would pass hydrogen sulfide through a sample 0:22:58.880 --> 0:23:03.439 fluid and that would create a reaction that would release hydrogen. 0:23:04.040 --> 0:23:07.000 The hydrogen would carry particles of arsenic as it bubbled 0:23:07.040 --> 0:23:10.480 up through the sample. And it's in gas form, so 0:23:10.600 --> 0:23:13.400 it passes through you know it'll it would just dissipate 0:23:13.440 --> 0:23:15.040 if you didn't have anything else attached to it. But 0:23:15.080 --> 0:23:18.320 you would have your your device set up so that 0:23:18.800 --> 0:23:22.199 the gas is passing through a line like a glass 0:23:22.200 --> 0:23:26.359