Science Vs - Forensic Science

Episode Date: October 7, 2016

There are a slew of scientific techniques that forensic experts use to solve crimes. But how reliable are they? We’re putting forensic evidence under the microscope. To help us crack the case, we talk to Assoc. Prof. Sibyl Bucheli, attorney Chris Fabricant, former crime lab director Barry Fisher, Dr. Itiel Dror, and Assoc. Prof. Patrick Buzzini. Our Sponsors Hello Fresh – To get $35 off your first week of deliveries visit hellofresh.com and enter promo code “ScienceVS”. Frank & Oak – Go to frankandoak.com/science to get your first outfit for $79 (a pair of pants and a shirt). Wealthsimple – Investing made easy. Get your first $10,000 managed for free. Credits This episode has been produced by Wendy Zukerman, Shruti Ravindran, Diane Wu, Austin Mitchell and Heather Rogers. Our senior producer is Kaitlyn Sawrey. Edited by Annie-Rose Strasser and Caitlin Kenney. Fact checking by Michelle Harris. Sound design and music production by Matthew Boll, mixed by Martin Peralta and Bobby Lord. Music written by Bobby Lord. Selected References 2009 National Academy of Sciences and 2016 President’s Council of Advisors on Science and Technology reports on forensic science Overview of forensic entomology Amendt et al, “Forensic entomology,” Naturwissenschaften, 2004 Study modeling precision of dating time of death from flies Faris et al, “Forensic Entomology: Evaluating Uncertainty Associated With Postmortem Interval (PMI) Estimates With Ecological Models,” Journal of Medical Entomology 2016. Review paper on bite mark analysis Clement et al, “Is current bite mark analysis a misnomer?” Department of Justice review of Brandon Mayfield case Context can change how fingerprints are read Dror et al, “Contextual information renders experts vulnerable to making erroneous identifications,” Forensic Science International, 2006. Hair microscopy can lead to incorrect matches Houck et al, “Correlation of microscopic and mitochondrial DNA hair comparisons,” Journal of Forensic Science, 2002. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Think of it as your guide for all things AI, with the most human issues at the center. Join me every Wednesday for Pioneers of AI. And don't forget to subscribe wherever you tune in. Gimlet Media's Science Versus. This is the show where we pit facts against fugitives. On today's show, forensic science. How much can you trust the science being presented in courtrooms? Forensic science uses scientific methods to investigate crime and prosecute people. We've all watched the telly. We know how this works.

Hodges ran the formalin-fixed tissue sample from Jane Doe 99 through GCMS. There's no traces of ecstasy, but he did find chloral hydrate. And if you need iced tea to translate for you... I hope you like hot wings. We're on the next plane to Buffalo. Forensic science has been used by law enforcement to catch and prosecute people for decades.

Experts have gone into court testifying that they can match a strand of hair or a set of fingerprints to a suspect, and that testimony has been used to lock up countless bad guys. But what if they're not all bad guys? Recently, big questions have been raised about the credentials of forensic science. Questions like, is forensic science even a science?

Sick burn, huh? Over the last few decades, the United States has freed more than 100 people whose convictions were partly based on forensic science evidence. And that's part of the reason why two of the most trusted science groups in the United States decided to take a critical look at forensic science. The National Academy of Sciences published their report in 2009 and the President's Council of Advisors on Science and Technology published

their report earlier this year. Both of these reports questioned the validity of some forensic sciences and pointed out serious shortfalls in expert testimony. So, when it comes to solving crimes, there are lots of CSIs. The CSI New York, Miami, Las Vegas, cyber. Cyber? Ugh. But then, there's science. There are a lot of areas of forensic science, from ballistics to drug testing to fibre analysis. But today, we're going to focus on the forensics that relate to the human body. These are some of the oldest forensic sciences

and they've been convincing juries of guilt or innocence for decades. First up, time of death. Using the best science available, how accurately can investigators tell when someone has died? Two, bite marks. Can you match a bite mark to a suspect's teeth? Three, fingerprints. How reliable are they?

And four, hair. When a strand of hair is found at a crime scene, can you use a microscopic analysis to find out who left it there? A quick warning, today we're going to be talking about dead bodies and crime. So if you have kids with you, you might want to slip on some earbuds or save this episode for later. Let's start with time of death. One of the first things that forensic scientists are often called in to do

at a crime scene is to figure out when someone died. You can check the body's temperature or how stiff it is or even do an autopsy. But if it's been more than four days, accurately predicting the time of death by just examining the body becomes a lot harder. For times like this, you need to call in a bug expert. Where is the bug man when you need him?

They'll inspect the corpse for bugs that move in when the flesh has begun to rot. Sibyl Bouchelai is an Associate Professor of Entomology at Sam Houston State University in Texas. Our producer Caitlin Sori and I visited her in her office. Her office door is covered with inspirational posters. If you took all of the veins from your body and laid them from end to end, you would die.

When work feels overwhelming, remember that you're going to die. That's pretty nice. Science fact. Handy poster to have. Sybil is all about bugs. She researches them and since 2008, police have regularly called Sybil to check out the bugs at a crime scene. And she gets pretty excited about her work. I feel that all the time though.

What are we going to do now? Science! Sybil tells us that if you want to use bugs to tell how long a person has been dead for, you've got to figure out how old the insects that are crawling on the corpse are. Flies turn up on a dead body almost immediately. They'll start eating the body and then they'll really move in. They'll fall in love, they'll start making fly babies called maggots, and when the maggots grow up, they crawl off the body,

they make a little shell for themselves like a cocoon, and then they'll escape out of their shell and fly away. For all the cases I ever do, what I'm looking for are the oldest maggot. And what that's going to tell me is how long that body has had fly activity. Different species will colonise the body at different times. Blowflies, for example, like a fresh corpse, and they can colonise the body really quickly. Now, in the best- case scenario for Sybil,

the flies will get to make and fly babies right away. They'll lay their eggs and she will catch the first generation of maggots. From here, Sybil says that she can date the corpse with remarkable accuracy. I would look at age of the maggot and then that would get you today. That would get you today? Wow. It can. It can get you today. A paper published this year looked at the accuracy of this technique.

It modelled how different conditions, like places and seasons, can affect death estimations using bugs. In the best case, the paper found that reading the bugs on a body got it right to within one day. Change the conditions though, and the estimations could be wrong by up to 19 days. When would that process not be as accurate as you'd like it to be? If the death occurred in the winter and the remains were placed outside, there might not be a lot of insects around. And they wouldn't colonise the cadaver until temperatures warmed up enough.

On top of that, there are always surprises. Like, here's a weird one. There's some evidence that if the victim died with cocaine in their system, the maggots would eat that up and can be found talking someone's ear off at a dance party. No, they don't do that. They don't talk. Actually, when bodies have cocaine in them,

there's some evidence to suggest that the maggots will grow up faster than they usually would, and this can affect the assessment of the time of death. Plus, in some cases, flies might get to an injured person before they're even dead. Don't think about that one while you're having breakfast. Sybil is still uncovering new things about which bugs turn up and when. She and her team are constantly doing experiments researching this,

and she told us about one time when her team made a two-inch cut into the belly of a corpse. They then buried the body in a shallow grave. And then the team waited for the flies to show up. But this time, a very different bug got to the body first. Fire ants. They were taking dirt, putting it in the fluids of the wound, and then they would pick up the soggy piece of dirt

and bring it back to the nest, possibly to slurp it up later. They were using the dirt as sponges, and they did this for nine days. And then on the ninth day, it rained, and it warmed up, and the body blew up like a volcano. Just all the guts came out.

And at that point, the fire ants lost their monopoly of this small incision and the flies were able to come in and lay eggs. So that's an example where the fire ants could have interfered with the estimation by nine days. Wow. And that if you hadn't, if someone, so if someone just came into that dead body and just saw the maggots there. They would think, yeah.

And they saw like eggs and itty bitty maggots, they would think that that body had been there for maximum an hour or two. Given all of these variables, the weather, the fire ants, the cocaine, researchers are still working out how often they get their estimations for the time of death using bugs wrong. Researchers from Texas A&M University wrote in a paper earlier this year that the accuracy of these estimates, generally speaking, are, quote, unknown, end quote. Sybil says that if your entire case rides on an entomologist, a bug expert,

then your case is probably really bad. She says you need other types of evidence as well. Bugs are just one tool. Conclusion. Using flies to date a body has solid science behind it. We have a good idea of the life cycle of a fly and how quickly they grow once they've infested the body. But since each crime scene is different,

you can't always rely on the bugs. Next up, bite marks. Bite marks have been allowed as evidence and routinely accepted in legal systems for decades. They've been used to investigate sexual assault and murder cases around the world, including in Australia, the UK, Norway and the US. Perhaps the most well-known case was of a serial killer, Ted Bundy.

Two bite marks found on one of his victims were linked to Ted and this dental evidence helped secure his conviction. But bite marks had a really unusual entry into US courts. The first ever recorded victim in a bite mark legal case wasn't a person. It was a piece of cheese. Cheese? Yeah.

Yep. Cheese. We heard this story from Chris Fabricant, who works at the Innocence Project. This is a group of lawyers who work to overturn convictions. They've recently been working with the FBI and Department of Justice to look into cases where faulty forensic science has been used. So, back to the cheese.

Chris told us that the scene of the crime was a grocery store in a small Texas town in the 1950s. A burglar had taken a bite of a piece of cheese and some enterprising young detective had found this piece of cheese and deduced that if we could find the person who bit this cheese, we have our burglar. The sheriff suspected a local drunk of robbing the store, so he gave him another piece of cheese to bite into.

The detective then made a cast of that cheese as well as the one from the store. He compared them and said, boom, they're a match. The police department brought in a dentist who agreed with the cop. What a good a day at work. They matched that cheese to the suspected burglar and we had bite mark evidence. Tasty or brie?

You know, the truth is, I don't know what kind of cheese it was. Can you brie? You know, the truth is, I don't know what kind of cheese it was. Can you brieve him? Nah. OK, that was back in the 1950s. Bite mark cases eventually moved from matching marks on cheese to skin and they're still used in courts today. So here's how bite marks work today. Forget about the cheese.

Say you have a body that's got what looks like bite marks. A photograph is taken of the patch of skin with the mark, and if there's a suspect, a mould is made of that person's teeth. A dentist then takes this mould and uses it to bite something, like pig skin or even a cadaver, a dead body. She then takes the photograph of this second mark, and then she puts the two photos side by side, one from the crime scene and one from the suspect's teeth.

She compares how similar the bite marks are and if they look very similar, then boom, it's a match and your suspect did the biting. To see how this all happens in real life, we spoke to Barry Fisher, a forensic scientist who headed up the LA County Crime Lab, one of the biggest crime labs in America. By the way, crime labs are often part of police departments and it's where cops

send their evidence to be processed by forensic scientists. Barry is now retired, but he remembers when he first arrived in LA all those years ago. The twinkling lights on the palm trees, it was at night when I got in, were magical a la Disneyland. I said, boy, this is wonderful. This is the place to be. Barry stayed in LA and ended up heading up the crime lab for 22 years. He's now retired. When he was head of the crime lab, he represented the squad as the president of the American Academy of Forensic Sciences. The thing is, even Baza has some concerns about bite mark evidence. For one, he told us that if you bite into skin, it bounces back.

It can be stretched and contorted. The problem with skin is it's elastic and it's a representation of the bite, but it's not going to be an exact representation. Another problem is that you can't reliably tell people's teeth apart. In 2010, a study looked at hundreds of sets of teeth and found, quote, uniqueness cannot be demonstrated, end quote. In a follow-up study using more than 1,000 3D-scanned sets of teeth, it found, again, that teeth don't vary that widely from person to person. And there's one more thing you should know.

There have been instances that have been reported where some experts have claimed it to be a bite mark and others have said, no, it's not a bite mark, it's a scratch. Yep, a scratch. Earlier this year, that report by the President's Council of Advisors on Science and Technology wrote on the topic of bite marks that examiners, quote, cannot even consistently agree on whether an injury is a human bite mark, end quote. And so in April this year, after a six-month investigation,

the Texas Forensic Science Commission unanimously recommended a moratorium on the use of bite mark analysis until the science improved. But the thing is, the President's Council report, the one we mentioned at the beginning of the show, wrote in September this year that bite mark analysis was so bad that it may not be, quote, salvageable, end quote. And yikes. And yet, despite the overwhelming scientific consensus that bite mark analysis is unreliable,

some dentists, rebranding themselves as forensic dentists, have been going into court saying that they are certain that teeth marks found on a body belong to a suspect. Right now, Chris over at the Innocence Project has clients who are on death row because of cases that included bite mark evidence. Halfway through our conversation, he got a call from a colleague about a case he's working on. This is a good start, yeah? Mm-hm.

Mm-hm. Well, we're on the side of science. Mm-hm. I guess the judge is not going to want to hear from me. All right, we'll talk, no problem. We'll talk to you soon. What was that about? It's a death penalty case in Pennsylvania where the prosecution is seeking to introduce bite mark comparison evidence and we are seeking to challenge the admissibility of that evidence. It's not clear how often bite mark evidence is introduced into court these days.

No one keeps reliable records on this. But for Chris, these cases just keep popping up. Sometimes it feels like whack-a-mole, you know what I mean? And sometimes it just feels like moles with no whacking. It's a process, never-ending process. It would be funny if there wasn't an innocent man on death row. Conclusion. Saying in court that you can definitively link a bite mark to an individual is bad science. Teeth aren't that unique and neither are the bite marks they leave behind on stretchy skin.

After the break, getting fingerprints from a bloody crime scene and a big FBI bungle. Welcome back. It's time to talk about fingerprints. Fingerprint analysis has been used for more than a century by investigators at crime scenes and prosecutors in court. And it's been used in some pretty amazing cases. Our forensic scientist Barry told us about one of his first cases involving fingerprints.

It was from the 1980s. A woman was found dead in East LA. She'd been stabbed and on her stomach something was written. Written with some creamy substance. It's spelled out F-U-C and then he ran out of room. It was pretty obvious what the perpetrator was trying to spell out. Barry found a squeezed out tube of moisturizingising cream in the woman's handbag, so his job was to try to get a fingerprint off that tube. But the tube was all crumpled up, so it was tough to get clean prints off it. It was then that he came up with a very clever plan.

Barry used to carry around this handy toolbox with all sorts of gadgets, including a syringe. So he put the cap on the tube and closed it tight. Then I stuck the syringe into the bottom of the tube and I pulled out the plunger and I blew it up and just puffed, puffed right out. It worked. The team was able to get some pretty clean prints off this very crummy tube. It just kind of surprised me that how such a simple, obvious thing just did the trick. Barry says the fingerprint on the tube was a match for the woman's boyfriend. And as Barry tells it, when the boyfriend was confronted with the prints, he confessed to the crime. But the question for us is how do forensic

scientists know it's a match? On TV, they show fingerprints running up against a database until you hear that satisfying jerk followed by a... Russell Huntley's prints are on the Jupiters. That's not surprising. And if you need iced tea to translate for you... First spit that lollipop out before I smack it out your mouth. But the science is just a tad more complicated. Fingerprint matching technology

doesn't match up an entire fingerprint, swirl for swirl. Instead, they match up certain features on the fingerprint, like the point where the ridges end or split off. And there's no consensus on how many features need to be the same to call two fingerprints a match. Some countries say you need at least 12 points, some say 7 or 16. Still other countries, like the US,

don't have any minimum number at all. This is ultimately because experts don't actually know how unique any of these points on a fingerprint are. Large population studies on the uniqueness of various features on fingerprints haven't been done. Plus, on the TV, these points of similarity are all matched on computers. But like most dreams of technology, where's my jetpack? The technology just isn't that good. At the FBI, one of the best forensic crime labs in the world,

there is a database of millions of fingerprints. But it only gets you so far. Here's Barry. We haven't gotten to the point where we're relying on computers to say it's an identification. What we're still using is a human being to have a look at this stuff. So a computer will throw up potential matches. The FBI told us it's typically three.

And then it's up to humans to narrow down those matches to an individual. And as Stalin once said, once you've got people, you've got problems. Well, it sounds like something he would say. Which brings us to this guy. My name is Dr. ETL. And you pronounce ETL like the letters ETL. You know the movie ET? So it's an L.

ETL. You know the movie E.T.? So it's an L. E-T-L. Yes. Perfect. And you can say it a bit faster if you practice it a lot and say E-T-L. Thank you. Dr. E.T. Eldraw at the University College London researches cognitive bias in experts. Or as he puts it, When smart people do stupid things, when do competent experts make mistakes, not because they're not motivated or drunk or whatever. So ETL says that all humans, dumb, smart, drunk, sober, have biases. And this can become a problem when analysing fingerprints.

When it's not easy call, it's not clearly a match or not a match, then there's more interpretation. Subjectivity is involved. It's not totally objective. It's not CSI Hollywood. Now, these issues with fingerprints weren't really considered to be a problem until this happened. There's been a devastating terrorist attack in Spain. Without warning, a coordinated series of rush hour explosions struck three train stations in Madrid. In March 2004, bombs were detonated on several trains in Madrid, killing around 200

people and leaving more than 1,800 injured. Spanish authorities recovered fingerprints on a bag of detonators and then sent them to the FBI laboratory to help get the culprit. Because as we mentioned before, the FBI has one of the best forensic laboratories in the world. The FBI ran their prints through their database of millions of fingerprints and it suggested 20 candidates. It was then, as usual, up to the FBI examiner to compare the prints found on the bag to potential matches. One of those 20 potentials was an attorney based in Portland, Oregon called Brandon Mayfield.

The fingerprint examiner claimed there were 15 distinct points on Brandon's fingerprint that matched the ones on the detonator bag. And so the examiner said it was a match. The prints were then sent to three other experts and all four of them agreed that the print on the detonator matched Brandon's. Meanwhile, the FBI got busy rifling through Brandon's records and surveilling him.

They found out that Brandon was Muslim and he'd defended a convicted terrorist in a child custody case. Soon, Brandon was arrested. But then, around two weeks later, the Spanish authorities said they had found another match for this print. A man who, unlike Brandon, was actually in Spain at the time of the bombing. The FBI admitted they screwed up. They offered him $2 million and apologised.

Here's Brandon speaking after the fact. I honestly felt like I was being framed because I hadn't been out of the country for over 10 years. And a year and a half later, the Department of Justice put out a report trying to figure out what went wrong. Their report highlighted a couple of things. First, they pointed out that the prints, Brandon's and the ones found on the bag, had an unusual similarity. That is, they really did have a bunch of matching points.

But the FBI also acknowledged that there were some problems in their process. Like at one point in the investigation, this was after the initial match, the fingerprint examiners knew that Brandon had acted as an attorney for a convicted terrorist and that he was Muslim. The Department of Justice noted that one of the fingerprint examiners admitted that if the person who had been identified had been a different kind of person, quote, like the Maytag repairman, end quote, the lab might have caught the error. OK, so Brandon's prints apparently did look a lot

like the prints on the detonator bag. But the Department of Justice report noted that examiners began to find more features in the fingerprints that looked similar, which, quote, were not really there, end quote. What seemed to be happening was the examiners were focusing on similarities with the fingerprints and they were explaining away the little differences they saw. And then when other examiners saw the prints, they might have been influenced by what their colleagues thought they saw. ETL has a phrase for when this kind of thing happens, the snowball bias effect.

It biases more and more elements and more and more people involved. Their bias gets very, very big, like a snowball. That's why I call it the biased snowball effect. And everybody is happy we sent the guilty person to jail. So ETL watched as the FBI fumbled the Madrid bombing case and he couldn't stop thinking about context and bias. So he ran a little experiment of his own. He gave five fingerprint examiners two sets of fingerprints. One, he said, was Brandon Mayfield's,

the American accused of the Madrid bombing. And the other, he said, were the prints found on the detonator bag. Now, the experts knew that this was a high-profile case that had been bungled. So, perhaps unsurprisingly, four out of five of these experts said that the prints did not match. But the thing is, ETL had tricked them. He didn't give them Brandon's fingerprints

and the prints on the detonator bag. He actually gave each examiner a set of prints from a totally different case, an earlier case that each examiner had worked on and had once said were a match. This meant that thinking they knew the context of a case actually caused four out of five examiners to change their minds about whether two sets of prints were a match. Now, ETL's study was very small, only five examiners, but it was one of the first to look at how bias and context can affect fingerprint analysis. Since then, other work has also demonstrated

that fingerprint examiners can change their analysis depending on different circumstances. Now, it's important to note, though, that these later studies suggest that the impact of subjectivity is not as dramatic as what ITL found, with four out of five people changing their minds. An FBI study estimates that examiners get it wrong one in every 306 cases. Now how you feel about that error rate probably depends on where you sit in the courtroom. But Itiel doesn't want us to give up on fingerprints even though he studies the problems around them. He remains a big fan. Fingerprinting is one of the best forensic science evidence. Conclusion. Fingerprint analysis isn't perfect. It's complicated and there is human judgment involved. But still, it is a pretty good way to identify someone. The problem is that it's

not as infallible as many people and jurors think. Final stop, hair analysis. On TV shows, investigators are always combing through the crime scene, searching for that one telltale strand of hair. Take a look at this hair. I happen to catch a glimpse of this blonde hair in the zipper here. Hair. Detectives want to find a hair so they can match it to a potential suspect. Here's how it works. A hair turns up at a crime scene.

Examiners look at it under the microscope and then they see if it's similar to someone else's hair, like a suspect's. The idea is that there are teeny tiny differences within hair that are unique to each person. And we're not just splitting hairs here. This has been used in cases where people have been put on death row. For decades, the FBI went around the country training hundreds of experts on how to compare hair samples.

Here's an FBI training video from the 1960s. From a microscopic examination of hairs, we can determine race, body area. Hairs recovered from the victim's garment can be compared with hairs from a suspect. The people trained by the FBI then used that expertise in hundreds of cases, helping to put some people on death row. But what can looking at hair under a microscope really tell you about a suspect?

Patrick Bazzini is an Associate Professor of Forensic Science at Sam Houston State University. He told us that there was good science to tell the difference between whether a hair comes from a human, a cat or a dog. And Patrick says this is pretty obvious under a microscope. Oh definitely yes I think that the microscope is really the best instrument to make this type of determination is a must. Okay so there's good science to show this is a human hair. Where do we start getting into the bad science? What do you mean, the bad science?

I think you know what I mean. Yes, I was just teasing you, of course. In 2002, a landmark study found that in nine out of 80 cases where hair examiners had said the two hairs look the same under the microscope, they actually came from different people. So that means 71 out of 80 were right. That's not bad if you're doing a test and you're in primary school, but maybe not so good if you're sitting in a courtroom

and your life depends on it. Is it possible to take a hair sample from a crime scene and say, Wendy, this is your hair? Absolutely not. Not at least if there is the possibility that another unknown individual may have originated that hair. And while there might be teeny, seemingly special microscopic features in my hair, there are no good big studies showing how unique those features really are, which means that experts cannot say with any level of confidence that a certain hair came from a particular person. And the Department of Justice agrees. They acknowledge that you can't match a person to a particular strand of hair based on microscopic evidence. The problem is that throughout the 1990s,

courtroom experts were claiming that they could match a hair sample to a person. But today, the FBI is acknowledging the problems with hair. In June of this year, the director of the FBI wrote a letter admitting that there were problems with how their examiners were talking about hair comparisons in court. He said, quote, In many cases, we have discovered that the examiners made statements that went beyond the limits of science

in ways that put more weight on hair comparison than scientifically appropriate. End quote. Chris Fabricant from the Innocence Project says, My favourite example is actually a favourite example from Texas. The hair examiner in that case had said that the chances that somebody apart from the defendant had left the hair at the crime scene were slim to none and none just left town. As in the hair examiner said that there is no chance I'm wrong. I know this hair belongs to the suspect. The FBI is now working with the Innocence Project

to review more than 3,000 criminal cases that used microscopic hair analysis. As of March last year, the FBI announced that in 268 cases where the FBI testimony was used against a defendant at trial, in 96% of cases, wrong statements were made about hair analysis. 96%. In 33 of those cases, people were sentenced with the death penalty. Nine of those were executed.

Five died of other causes while on death row. Conclusion. There's no good scientific evidence that you can match a strand of hair to an individual by looking at that hair under the microscope. So, when it comes to forensic science, does it stack up? How accurately can scientists use bugs to tell when someone died? Well, under ideal conditions, they can nail the time of death to the day. But when things are unexpected, like fire ants or cocaine,

the science can get messy. Bite marks. Can you match a bite mark to a suspect's set of teeth? No. Teeth haven't been shown to be that unique and the bite marks that they make are even less unique. Fingerprints, how reliable are they? Most of the time fingerprint examiners get it right but they're not perfect and human judgment is involved. And hair, can you pin a suspect based

on a microscopic analysis of their hair? Nope. Science is not good enough to see hair under a microscope and match it to a particular person. But hair is very useful in other ways. There's a goldmine of information in the DNA of hair and that can pin a suspect to a crime. DNA has in fact become the gold standard of forensic science, and there's good science behind it with clear statistical certainty. DNA has been used to put guilty people away and set innocent people free. But forensic scientists have now started pushing the boundaries of what DNA evidence can do.

They're able to extract tiny amounts of genetic evidence from doorknobs, coffee mugs and even weapons in a way that just wasn't possible decades ago. A new generation of forensic science is upon us. But is it any better than the old stuff? That's coming up next time on Science Versus. We'll be back with part two of Science Versus Forensic Science in two weeks.

And when we do, we're getting our hands really dirty. So is this person wearing a shirt? No, that is what the flesh ends up looking like throughout the decomposition process. It looks like they're wearing clothes, but it's actually skin. This episode has been produced by Shruti Ravindran, Diane Wu, Austin Mitchell, Heather Rogers and Caitlin Kenney. Our senior producer is Caitlin Sorey.

Edited by Annie Rose Strasser. Fact-checking by Michelle Harris. Sound design and music production is by Matthew Boll. This has been mixed by Martin Peralta and Bobby Lord. Music written by Bobby Lord. I'm Wendy Zuckerman. Back to you next time.