How does DNA solve crimes? with DNA Today podcast

We are Shaking Things Up, DNA, and featuring a full-length episode from DNA Today, another podcast on our GenePool Media Network.

This episode came out on January 31st and features Dr. Henry Ehrlich, a pioneer in DNA analysis and a key figure in developing polymerase chain reaction, or PCR, technology. His work has transformed the criminal justice system from solving cases to overturning wrongful convictions. Please note that this episode contains discussions of murder and sexual assault, which may not be suitable for all audiences.

For more info and episodes from DNA Today, visit the website dnatoday.com. Let's get started. Music. How is it that we find ourselves surrounded by such complexity, such elegance? The genes of you and me The genes of you and me We're all made of DNA We're all made of the same chemical DNA, We're all made of DNA We're all made of DNA Hi, you're listening to DNA Today, a multi-award winning podcast and radio show where we discover new advances in the world of genetics.

From genetic technology like CRISPR to rare diseases to new research. For over a decade, DNA Today has brought you the voices of leaders in genetics in over 200 episodes. For the past three years, DNA Today has won the People's Choice Best Science in Medicine Podcast Award. I'm Kira Deneen. I'm a certified genetic counselor and your host.

The number one category for podcasts is true crime. So I figured, why not dabble? We can talk about the genetics of crimes and how we use DNA analysis to explore this. Joining me is Dr. Henry Ehrlich, a pioneer in the field of DNA analysis. Dr. Ehrlich was instrumental in developing polymerase chain reaction, or PCR, technology, which transformed forensic science.

With over 450 publications and decades of groundbreaking work, he's played a key role in applying DNA analysis to criminal cases, missing persons investigations, ancestor research, and so much more. After reading his book, The Genetic Reconstruction of the Past, I had so many questions about how PCR reshaped the justice system, its impact on exonerations, and ethical questions surrounding forensic DNA databases. All topics we get into in this episode.

I also do want to offer a trigger warning for murder and sexual assault. This content is not suitable for our young listeners. Dr. Henry Orlick, thank you so much for joining us. I am really excited, as I said, to get into the true crime aspects of genetics.

We really, I don't know if we've ever done that. So take me back to the mid-80s. The most novel technology in DNA analysis for criminal cases and other genetic studies that we'll get to was the development of polymerase chain reaction, which people know as PCR. And when I learned this in school, I remember Cary Mullis' name coming up and you mentioned him in the book.

But you were on the ground floor of this. And what, around 1985, you published the first account of PCR amplification on a specific human gene, HBB. And, I mean, it was just absolutely novel this time in the mid-'80s and looking back over the last 30 years of everything that has come from that that we're going to get into in this interview. But I figure we should start out, for people that aren't familiar with PCR. How does it work? And then getting into just the massive impact this has had

in genetics and really the world, I would say. Well, thanks, Girod. So, PCR basically mimics in a test tube the process of DNA replication that takes place in the cell. And what it is, is a system for creating millions and millions of copies of a specific DNA sequence using enzymes.

And the basic technique, as I said, follows a process of DNA replication in the cell, and that process involves separating the two strands of the DNA double helix, and then synthesizing using a DNA polymerase, an enzyme that copies and synthesizes DNA, using that enzyme to synthesize a new strand.

So if you start out with a single molecule and separate it into the two component DNA strands and synthesize a new strand of DNA using those original strands as the template, you've doubled the amount of DNA. And that's why if you keep repeating that cycle, it becomes an exponential reaction. So in the first cycle, you make two copies. Then in the next cycle, you have four. In the next cycle, you have eight. In the next cycle, you have 16.

So each cycle of DNA replication, where the strands are separated, you synthesize a new strand. And then in the next cycle, you separate them again and continue the process. That's why Carey Mullis, who first had the idea, referred to it as a polymerase chain reaction, because it's an exponential reaction. And the critical element is that you can direct the synthesis of a DNA fragment to a specific target.

So as you indicated in our original work, we were focusing on the beta globin gene, or HBB. So using short pieces of DNA called oligonucleotide primers, you could direct the activity of the copying polymerase to a specific region. So the HBB gene is just a very small part of the whole human genome. But when we were trying to see if Carey's idea could be actually made to work. We directed the oligonucleide primers to the beta globin gene and tried to see if we could amplify the beta globin gene.

So in a way, identifying a needle in a haystack and then creating millions and millions and millions of copies of that needle. So that's the essential idea of PCR. That is, you can target a specific gene or region and create millions and millions of copies of it so that you can analyze what you've amplified. And it's become so ubiquitous in so many areas of testing and genetics and how we're able to use that, which is what we're going to be talking about in these episodes.

Even for people, I think a lot with the COVID pandemic, a lot of people learn PCR because of the PCR-based test for COVID. But we've had this since, you know, the mid-eighths. But it's become more of a household term, I think, because of COVID. How does PCR outperform what the other test kind of was at the time, RFLP, if I'm getting the letters right? Yeah, no, you're exactly right. RFLP stands for Restriction Fragment Length Polymorphism.

And it's interesting that you should bring that up. That was a technique for analyzing variation in the DNA. today. And in the very first case that I ever worked on and that became the first DNA case in the world, Pennsylvania v. Pestinicus, in 1986, when my colleague and friend, Ed Blake, who's a forensic scientist, approached me with this problem, I said, well, we could try DNA analysis. And the first thing I thought of was RFLP and another related technique called the southern blot.

The reason that that didn't work in this particular case and didn't work in many of the other cases like the first DNA exoneration that we did was because RFLP as method of DNA analysis requires a large amount of DNA and it requires that the DNA be present in large fragments. That is, thousands and thousands of bases long. That's like a perfect sample, which you're not going to get in a lot of criminal cases.

Right. And so in this original case, where the crime scene evidence was an autopsy sample that had been stored in formaldehyde, the DNA was degraded into small little bits. The issue that my friend Ed Blake approached me with was he said, you know, I have this autopsy sample and I've been asked by the prosecution to analyze it.

But at that time, DNA had not ever been used in criminal cases, and all the only techniques that were available were blood typing, like ABO blood typing, or protein electrophoresis, where you could analyze variation in proteins based on their mobility in a gel, based on your electric charge, or some protein. Some other techniques that used antibodies to distinguish protein variants. So as it turned out, because of the formaldehyde storage, all of the proteins were what's called denatured.

So none of the current techniques that were available to Ed could be used on this. So as I said, I suggested we try DNA, and I suggested we try RFLP, but the DNA was just way too degraded. It was present only in small bits and only a small amount.

So I said, well, we could try this new technique that we had just developed called PCR. Because this was only a year after you published your paper because your paper was 85 and now this case was 86. So that is a quick turnaround time to be like, hey, let's use this technology that we just published about. No, that's exactly right. And that's a real insight because it's very unusual that in a courtroom, a brand new technique could be used to present data to the jury.

And just to kind of skip ahead, usually with a new scientific technique that's going to be presented in a courtroom in a criminal investigation, There is what's called an admissibility hearing where the adversarial members, you know, the prosecution, the defense, have scientific experts for each side. So kind of dueling experts, as it were. They make the case in front of a judge and then the judge decides whether the evidence is reliable enough to be presented to a jury.

Can we include this info in the case or can we not? Yeah, yeah. And so that's why it's called admissibility hearing. Is the evidence admissible? Can it be shown to a jury? And this was kind of an ironic instance because the prosecution had asked for the test and the results favored the defense. So that backfired. So therefore, usually one side will object. If the prosecution says this is a match, the defense will say it's unreliable and you have to sort this out in the admissibility hearing.

And if it's an exclusion, that is that the evidence does not match the suspect. That obviously favors the defense, and sometimes I've been involved in cases where the prosecution would argue that it was not reliable and shouldn't be presented to the jury. But in this case, it was presented to the jury because there was no one could object. The prosecution had asked for it, and it favored the defense.

So then they were like, yeah, let's include it. And the prosecution's like, I wish we didn't do that. Yeah, the prosecution couldn't argue, oh, this is totally unreliable because they were the ones who asked for it. So that was an interesting case. But anyway, the way that worked is, as I said earlier, we had tried RFLP, and the DNA was just much too degraded, too small fragments.

So I said we could try this new technique, and we had just amplified beta globin for the prenatal diagnosis of sickle cell anemia. And because I'm an immunogeneticist, the next gene we amplified and started to analyze was one of the HLA genes. These are genes that are involved in the immune system. They're the gene whose products are involved in initiating a specific immune response. And they're the ones that you see in all the medical shows of like, well, are they an HLA match?

Organization. I think that's how the public has heard of HLA, but them in itself, those genes are just so interesting. I mean, I'm preaching to the choir. That's your area. But just those genes in general are just so... We could do a whole series on that. Yeah, no, that's one of the reasons that I was so interested in analyzing these genes by DNA. And one of my. Pet projects, one of my, the focus of my research was trying to develop a DNA-based system for HLA typing.

That is a DNA-based system for distinguishing all the variation at these critically important genes, you know, genes that play a crucial role in the immune system. And I actually just, as a side point, when I said this was, you know, this was what I was going to do, There were lots of people in the field who said, oh, we don't need DNA HLA typing. We have serological HLA typing and it works just fine.

But of course, the amount of genetic diversity that was revealed by DNA typing was infinitely more than the serological types. You need a lot more information. If someone's going to get an organ, you want to see that it's as close of a match as possible to not have an immune response to that. Yeah. No, that's exactly right here. that this DNA-based typing made solid organ transplants much more reliable.

And especially bone marrow transplants, because bone marrow transplants or stem cell transplants, matching is even more crucial than it is with solid organ, because with solid organ, the recipient can reject the graft. But with a stem cell or bone marrow transplant, the recipient can reject the graft, But the graft can also attack the host. So those have to be matched extremely carefully.

And so DNA typing has, as it turned out, really revolutionized transplantation because it improved our ability to match in a very significant way. But anyway, coming back to these autopsy samples, I suggested to Ed that now we have a system for amplifying an HLA gene, and the HLA genes are very polymorphic. That is, they vary in the human population, so they would be useful for individual identification.

And so when we tried to amplify the gene HLA-DQ-alpha with our initial system, which used the E. Coli DNA polymerase, and it didn't work. But then I told Ed, we had just started using another enzyme from the bacterium Thermus aquaticus, and the DNA polymerase was what we call TAC polymerase. And TAC polymerase made PCR automatable. And it made it more efficient and specific. And you had to find something that

was going to work at really high temperatures. And wasn't that enzyme found in like the hot springs of Yellowstone? That discovery led PCR to work. Yes, that's exactly right. It just shows how many different strands of basic research can come together. It's a great example of that basic research leading to this technology. Yeah. You have to read the footnotes in the book to get that one. So I'm showing off that I even read the footnotes, right? Yeah, no, I'm impressed.

It's important, as one of my friends point out, it's important to read the footnotes because that's where all the jokes are. That is true. You've got some good jokes in there. I even highlighted some jokes because I was like, I want to go back and laugh at that later. But anyway, you're right. The bacterium thermos aquaticus was discovered and isolated from a hot springs in Yellowstring, Yellowstone Park.

And apparently now that's part of the spiel of Yellowstone Park rangers when they talk about the hot springs. But anyway... Test it out. I'll go there and see if they say. If they don't, then I'll share it with the crowd. It'd be a note at all. But anyway, using or incorporating the TAC polymerase into PCR really changed everything. Because with the E. Coli DNA polymerase, after each cycle where you heated the reaction to separate the DNA strands, you also inactivated the polymerase.

So you had to open the tube and add back new enzyme. With TAC polymerase, you didn't because it was resistant to high temperature.

So you could put everything in the tube and then just cycle the temperature in the tube and run 20 or 30 or 35 different cycles of PCR. That didn't forget it. Yeah. But then the other reason that it made it so much more specific that the short pieces of DNA that we call ligonuclidide primers bound to the template DNA, they could be bound to the template DNA at very high temperature where that meant they had to be perfectly matched.

But with the E. coli DNA polymerase, the step where the primer is bound to the template DNA was at 37 degrees instead of 70 degrees centigrade, and therefore some amount of mismatching was tolerated, so you got much less specific amplification. And that's why in the autopsy sample, we could really only get it to work when we use the TAC polymerase.

And when we got results from, we, as if I was there, when your team would get results from this and be using these in cases, there's a lot of terms that I had heard, but it was very helpful in the book that you defined them in terms of, And some of this even applies to what we were talking about with HLA matching with donation, inclusion, match, exclusion, and random match probability. So can we break down a little bit like what that actually means genetically in a case?

If you have a suspect, how do we have them be excluded, included, that term match, and then the RMP? Okay. Now, those are all very critical elements in interpreting DNA analysis in the criminal justice system. So if you have a crime scene evidence and you generate a profile from it and you have a suspect and you can generate a profile from that individual, you can compare them. And if they're the same or indistinguishable, if they match, that's referred to as an inclusion.

If they don't match, that's referred to as an exclusion. It can't be that person because one DNA marker doesn't match. That's right. So then, oh, all right, well, that person can't be the one that committed the crime if that's the sample of the criminal. That's exactly right. And one aspect of an exclusionary result is that no complicated statistical analysis is required. You can just infer, as you pointed out, that this sample could not have come from the suspect.

So, you know, end of kind of no statistics, end of story. Thank you very much. On the other hand, if they're indistinguishable, if they match, and it's what's called an inclusion, you still have to try to figure out what is the significance of the inclusion. But this doesn't mean it's a 100% match, where it's like, oh, this is the person. They're still on the running. Well, I would say it could be a 100% match in the sense that the profiles are identical.

But then the question is, what is the frequency of that profile in the general population? So if, let's say, they match perfectly, but 1% of the people in the general population would also match, so that still is significant evidence against this person, but it's not definitive. You certainly can't say definitively, oh, this came from that person. But if instead of 1%, you know, it's 1 in 100 million, then that's a very significant result.

You know, and it would argue very, very, very strongly that this evidence sample came from the suspect. So it's crucial to be able to estimate the frequency of that genetic profile in the general population. And the random match probability is a probability estimate that reflects the frequency. It basically is defined as saying, what is the probability that a random individual picked from this population would also match? So if that's, you know, one in five, your match doesn't mean very much.

If it's 100 million, it's hugely consequential. And it's important for that information to be presented to the jury as they're taking in this case. So here's the evidence that supports the idea that this suspect actually did commit the crime. Yeah, no, that's right. To just say it matches is almost meaningless. You have to say it matches and then provide some statistical metric like the random match probability.

And one of the things that I try to do in the book is explain how that random match probability estimate is generated. So it makes certain assumptions. Like, if your database of population is, let's say, Hausson, how could you ever say that the random match probability is 1 in 100 million? And the reason that you can generate those very large numbers is that you make an assumption of statistical independence that has to be consistent with the population genetics data.

But you make that assumption, And let's say if you have 10 different genetic markers... And the probability of matching at one marker is 1 in 10, you just multiply that. So it's 1 in 10 times 1 in 10 times 1 in 10. And so eventually you get to, you know, very, very high numbers. Submitting a research paper can feel like a black box, right? Which journal do you choose? What are editors actually looking for?

And how do you boost your chances of getting published? On episode 337 of DNA Today, we dove into the publishing process with two professionals from widely advanced portfolio, Dr. Lele and Dr. Alana Gannon, both deputy editors at Advanced Science. They share insider tips on how to pick the right journal, avoid common rejection red flags, and craft standout cover letters and reviewer responses.

I also learned more about open access publishing and how AI tools like ChatGPT are already changing the game. Whether it's your first submission or your 10th, this episode is packed with practical advice to set you up for publishing success. Thanks again to Wiley Advanced Portfolio for sponsoring the episode. Again, that's episode 337. Maybe put it in your podcast queue so it plays right after this episode.

And I want to go back to something you said earlier about like the first DNA-based exoneration, which I think was 88. I was surprised it was that late. It's a big end point. A lot of these numbers and dates surprised me in general. But what was heartbreaking is you say in the book, 575 convictions have been overturned based on DNA evidence as of 2023.

So when I assume you were editing the book and 21 of them were in death penalty cases, where if we had had DNA evidence back when these cases were being like, you know, pursued, the trial was happening. These people probably would not have been convicted because later DNA evidence was like, hey, you actually weren't the one that committed that crime. And it brings up this horrible concept where suspects have been coerced into providing false confessions.

Were those numbers surprising to you, just how many convictions were overturned, or were you kind of like, yeah, unfortunately, that's what we were thinking was going to happen?

Well, I have to admit I was surprised and disturbed I should point out that those numbers come from the Innocence Project Which was an organization founded by Peter Neufeld and Barry Sheck And they've done wonderful overturning wrongful convictions And DNA, as you point out, has been a huge part of that And I was also concerned and disturbed by the amount of coerced false confessions that several of the cases that I worked on, and the most dramatic case was Earl Washington Jr.

Case, to which I devoted an entire chapter just because it was so dramatic. He had confessed in the interrogation to a rape murder, and later in the trial, he denied that and said he was innocent. And he was actually scheduled to be executed a few days after. His defense attorney sent me the lab results, and I wrote a report.

And this is kind of a technical issue, but is at the heart of some of the difficulty in interpreting what are called forensic mixtures, when more than one person has contributed to the evidence or the crime scene, say, bloodstain or semen stain. And so I think I entitled that chapter of the Earl Washington Jr. Case and the problem with mixtures, because it was a problem with mixtures that led to his conviction and scheduled execution.

So just to try to simplify the situation, there was a semen stain, and this was actually the HLA-DQ-alpha. So it was the original test that we used in 1986, and this case, I think, was about 1994. Anyway, it was the same technology. And so let's say there are three different variants or alleles as a geneticist, let's say, three different variants, genetic variants found in this semen stain. So let's just say it's one, two, three, one, two, and three.

So right away, you know that this is a mixture. You know that more than one individual has contributed to this crime scene stain because one individual can have at most two different variants. You know, one from the mother, one from the father, a symbol that's different. So if there's three variants, you know it has to be more than one individual. And to simplify this, let's say that Earl Washington Jr. Had a one and a two. So he was a 1-2 heterozygote. His genotype was a 1,2.

And so the prosecution and the lab said, well, his alleles are present. There's a 1 and a 2 and a 3. But when I analyzed the data, I said the major genotype is a 1, 3, and there's a very minor 2 that can be detected. And since the victim was a 2... I was going to say, what's the victim? Because you can have those DNA mix. That's right. That in a semen stain, you often have the victim's epithelial cells present.

Epithelial cells. This simple interpretation of the data was that the assailant was a 1-3 and a little minor 2 contribution from the victim. So if the assailant was a 1-3, that means it's an exclusion because Washington was a 1-2. So that was the whole basis of my report, and fortunately, the execution was canceled, but he wasn't exonerated, fully exonerated, for a few more years until the true assailant had been identified.

Wow. So even though the DNA evidence did not support that he was the perpetrator, he still was sitting in prison waiting. Yeah, well, I'm trying to remember whether he was released from prison. I think— I can look and update the show notes. I'll reread that chapter. Yeah, but he wasn't fully exonerated, that is, declared innocent until Kenneth Kinsley, the true rapist murderer, was identified by DNA analysis. And so, you know, I say that the Earl Washington Jr.

Illustrates, you know, three fundamental issues with the criminal justice system. One is technical, that it's very difficult to interpret mixtures. It's much easier now than it was in 1994, but it still can be difficult. And the second is the problem of coerced false confessions, that these are disturbingly more common than we would ever have imagined.

And the third is there's a tendency for the prosecution to be reluctant to overturn a wrongful conviction until the true assailant has been found. And as you're pointing out here, that, you know, basically once you've shown that someone is innocent, that should be the end of it. You shouldn't have to wait till the real assailant has been identified.

Because who knows how long that will take, if ever. There are unsolved cases, plenty of them. And it was surprising to me that it wasn't until 1998 that the FBI established the first national criminal DNA database. So NDIS, which is part of CODIS. Do people say CODIS instead of saying the letters? Am I getting there? Yeah. No, you're right. The TV show. So yeah. So who is included in these databases? Because who should be included and who is included?

Like there's been a lot of turmoil in the field of like who should be included in these. Yeah, no, that's a very good and important point. So, first of all, there are different kind of databases. So, the kind of databases that you use to calculate a random match probability are just so-called population databases. You know, Native Americans, Asian Americans, African Americans,

Caucasian Americans, Hispanic Americans. So. And they just contain DNA profiles. And they're the ones that are used to estimate the frequency of a specific genetic profile. But the kind of databases that are sent for in suspectless crimes, and there are a lot of these, obviously, that you have a genetic profile from crime scene evidence, but there's no suspect with whom to compare the profile. So in that case, one option is to search a database to see if you can find a match.

So the first kind of criminal databases were convicted felons of violent crimes. Then some states have allowed criminal, I should say, databases of arrestees. Some states have outlawed searching databases of arrestees. but those were the kind of databases that could be searched to find a match. And originally, all the searches were just for a perfect match. It's the person who contributed this crime scene evidence, someone who was in the database.

But after some time, there was a new strategy to look for partial matches in the database, and that was called familial searching. And so, if you don't find a complete match in the database, you can see if there's someone in the database who has a partial match with the evidence, and that would suggest that some relative of the person in the database was the actual assailant and the contributor of the crime scene evidence.

So familial searching now is kind of a standard part of database searching in suspectless crimes. Well, I would say very recently, in the last four or five or six years, searching genealogical databases has been used. And the first case, I think, in investigative genetic genealogy, which is what this is called, identified the Golden State Killer, who was a serial murderer and rapist.

And there were no matches in the criminal database and there were no complete matches in any of the genealogy databases, but there was a partial match. And the way genetic genealogy works, if you get a partial match in a genealogy database, you can then construct a family tree and go back and then look at all of the descendants of that family tree who might have had the opportunity to commit the crime and look at their DNA.

And that's how Joseph D'Angelo, a retired police officer, was identified as a Golden State killer. And was it, it was a cousin or a second cousin? It wasn't a real close degree family member. Yeah, no, that's right.

With genetic genealogy and where you have the ability to reconstruct these family trees, You can use a distant relative to go back in the family tree and then identify descendants of the people identified in the family tree who might have had the opportunity, who were in the same area where the crime was committed. And it's interesting, like 23andMe Ancestry, those require a core order. But then GEDmatch or GEDmatch was a public database.

Is it still going? I don't know. Yeah, it's still going. It's still going? It's been acquired by a forensics company. My understanding is the current procedure is that the DNA profiles can be searched only if the individuals who contributed the DNA profiles have consented to their being searched for law enforcement purposes. Like an opt-in process and people are voluntarily uploading their data to begin with, but then checking off an extra box or something to indicate. That's exactly right.

They're uploading their data for genealogical reasons, to find distant relatives, things like that. But they can check a box that said it's all right to search this for the purposes of law enforcement. Yeah. So it's just interesting that it's like the Golden State Killer case. That was monumental. I mean, everybody, I was in grad school when it happened and everybody was talking about this and like, this is going to change the game.

And just you think about these databases that have so much people's data in there to connect with, to make a family tree. All it takes is one even distantly related person to be able to kind of potentially link it back to them. And you brought up another interesting bioethical concept within these partial matches, especially for the government databases. And we're talking about the U.S.

Here specifically, that when we do family searching through databases, we're going to, It, as you explained, contains people who have already been either arrested, they're already a felon, some degree of this. And that depends what state or, you know, even the federal level. But is that going to or has it already exacerbated the like existing racial inequalities? Because people that are not white are arrested far more often than white people.

So when you're running this sample and saying okay this is the dna information let's see if it if we get any partial matches if we get any hits you're going to end up identifying more people that are not white and so is it just going to snowball and become a much bigger issue well yeah you're right that is an issue that i discuss in the book and i actually was interesting in the book.

I write about a discussion I had with my son, who was at that time working for Kamala Harris in the Attorney General's office. And he was the one who pointed out that the existing racial disparities in the criminal justice system, and therefore in the criminal database, would just be exacerbated by this familial searching. But my view is that the value of identifying criminals was a benefit to all communities, whatever their ethnicity.

So while acknowledging that there do exist racial disparities in the criminal justice system and therefore in the databases, that it was still, for society, a useful thing to do.

And one of the ironies now is that with the genealogy databases, this argument about racial disparities sort of goes away because... I was thinking that too. If you start looking at the other databases, that has way more people of recent European ancestry than anybody else. So does it balance out if we're also using those databases? Yeah. Yeah, no, it is interesting. And I've been saving one of my favorite questions here for last, because I can't interview you and not ask you about the O.J.

Simpson case, because you were actually somewhat involved in this. And it was a little before my time. So what I've learned from it is just from documentaries. I didn't live through the news, but obviously that's all anybody talked about in that time. It was just quite an interesting case for people that are younger than me. Go look into it.

You were actually scheduled to testify and you had the opportunity to review a lot of the DNA results. What did you learn? What were your thoughts on the case? How did this change public perception of DNA evidence used in cases? Because we've talked about earlier than this were the first times it was used, but those cases didn't really hit laypeople. This maybe was the first or the biggest, at least, for people to talk about, oh, the DNA evidence and this and the glove and everything.

So what did you learn? What were your thoughts by just looking at the DNA results? Well, first of all, you're quite right that I think it's this case that really brought the idea of DNA analysis in criminal cases to the general public. I suppose all the CSI... Yeah, that too. That gets a shout out in the book too. Well, too, but you're right that this case really established the importance of DNA analysis in the public imagination.

You know, my role was to analyze, review all the data, and I was scheduled to testify in an admissibility hearing that would be in front of the judge to see if the DNA evidence was reliable enough to present to the jury. But as it turned out, Peter Neufeld and Barry Sheck, who founded the Innocence Project, and they needed DNA to be reliable for all of their exoneration work.

They ended up stipulating, the technical term is they stipulated that DNA technology per se was reliable, so there was no need for an admissibility hearing. Like it should already be automatically included. Why are we asking if it should be included? That's right. They stipulated, yes, it's reliable. We do not need an admissibility hearing. And therefore, I didn't have to testify about the admissibility of the evidence.

But their strategy was to create other doubts in the mind of the jury that either the Los Angeles Police Department had contaminated some DNA or. That was an interesting part, EDTA of like, why is that there? Because for, you know, a lot of genetic counselors listening and lab people, that's what we use. That's purple top tubes, the lavender top tubes have EDTA. Yeah. So that's to make sure it doesn't coagulate the blood. right, to make sure it's staying fluid so we can use it for testing.

So usually that's added to a sample. That's usually not just naturally there. So that was a whole, I had never even heard of that before reading your book. Yeah, no, that was a red hair. One of the reasons that I know so many details of this case is that, you know, I was following it and I reviewed all the data, but my friend Ed Blake was also on the defense team. And that was kind of a philosophical discussion I had with Ed that the DNA evidence was overwhelming.

So I think to an objective observer, there was no question but O.J. Simpson did the crime. But I think the view of Ed and some of his colleagues on the defense team was the trial is not about the truth. It's not about whether he did it. It's about whether the prosecution made their case.

Did they do everything in the way they were supposed to? Because we have certain pieces that are thrown out because the police and everybody behind them did something that means, oh, well, now we can't pursue it. Like kind of getting out on, there's a term for that, just, you know, something that they didn't do right. Like if you don't read someone there, Miranda writes, oh, well now we can't pursue something. Technicality. I think that's the word I was looking for. Yeah,

right. So that view is that a trial, you know, is a competition and the prosecution has to make a compelling case for a conviction. And so their case, their view was the prosecution didn't make a sufficiently compelling case. But, you know, the DNA evidence was clear. And, you know, I come to this as a research scientist, not as someone, as a lawyer involved in the criminal justice system. So I had lots of discussions with Ed about this.

You know, I guess my view was the DNA evidence was pretty compelling. And the defense team was able, using various strategies, to create some doubt in the minds of the jury. Yeah, it certainly was one that is just still boggles the mind of like how that happened and everything.

Well, thank you so much, Henry. I mean, this has just been so interesting. I wish we had hours because, I mean, and it's amazing that this book isn't 500 pages long. When I think about how much I learned in it, it's like 180 pages, which made it a very quick read, especially with how interesting it was. I got to go to bed here, but, you know, let me finish the chapter.

So, I mean, thank you so much. This is just so interesting, and especially, as I mentioned at the top, True Crime is the number one podcast category. So it's kind of fun to tip my toes in the water here, but thank you. Yeah, it's been a pleasure. It's been fun. For more information about today's episode, visit DNAToday.com, or you can also stream all 200-plus episodes of the show, including video versions of interviews recorded in 2021 or later.

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