There’s Less Science In Forensic Science Than You Think

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Bite marks, blood spatters, fingerprints, hair samples– these are just some of the kinds of evidence law enforcement might collect when investigating a crime.

And if you’re a fan of crime TV, you might have a sense of what happens next. The sample goes to a lab, the scientists in the lab do science, maybe something like this clip from CSI Miami.

RYAN WOLFE: This is a jacket worn by our suspect, Hector Rivera. We believe that he stabbed Gabriel Cervantes. So I’m going to run what’s called a luminol test.

MIKE DOYLE: Yeah, what’s luminol?

RYAN WOLFE: Luminol is a compound that, when it interacts with the iron in hemoglobin, it’ll luminesce.

MIKE DOYLE: You mean, blood?

RYAN WOLFE: Yeah. Nothing vanishes without a trace, especially blood. Stabbings are very bloody, so if there is blood on this jacket, luminol will cause it to glow.

MIKE DOYLE: Oh, cool.

RYAN WOLFE: Another word for it is evidence.

IRA FLATOW: And fairly quickly, on TV, and in a little less than an hour– because as the show runs– the answer comes back. It’s definitely, absolutely, 100% a match for the suspect. But that’s not quite how it really works.

And in 2009, a report from the National Academies of Science, Medicine, and Engineering outlined a major problem with some common disciplines within forensic science. There’s just not much science to back them up.

The FBI even admitted in 2015 that, for decades, investigators had overstated the accuracy of hair sample matches over 95% of the time in ways that benefited the prosecution. And just last month, Attorney General Jeff Sessions decided not to renew one group that was working hard to bring science more into the picture– President Obama’s National Commission on Forensic Science.

So where exactly is the evidence dicey on forensic science, and what’s next for scientists, lab specialists, lawyers, and judges who want to see more rigor? That’s what we’re going to be talking about. Our number is 844-724-8255. You can also tweet us @scifri.

Let me bring on my guests. Dr. Suzanne Bell, a professor of forensic and analytical chemistry at West Virginia University in Morgantown. She’s a former member of the now-disbanded National Commission on Forensic Science. Welcome to Science Friday, Dr. Bell.

SUZANNE BELL: Thank you for having me.

IRA FLATOW: Betty Layne DesPortes, president of the American Academy of Forensic Sciences and a criminal defense attorney in Richmond, Virginia. Welcome to Science Friday.

BETTY LAYNE DESPORTES: Thank you for letting me be here.

IRA FLATOW: You’re welcome. First of all, what did you think of that CSI clip? Is luminol– do you use luminol to find the blood stains just like they do?

SUZANNE BELL: Yes, you do. And it’s quite effective for that. And his explanation was pretty good.

IRA FLATOW: So they’re doing some good work, at least the people who check the science on that script.

SUZANNE BELL: In that instance, sure.

BETTY LAYNE DESPORTES: What they do wrong, though, is that they tend to think that you can solve it in an hour.

SUZANNE BELL: Right. If only.

IRA FLATOW: How long does that test take, actually?

SUZANNE BELL: Well, for luminol, for the results, it’s very quick. I mean, unless– you know, it depends. If you have to do this indoors, and you have to black out, it’s a little more complicated than that. But the chemical reaction works quite rapidly.

IRA FLATOW: Let me go back to the point that you made, when you said they can do it that quick. How quickly does it really happen in real life?

SUZANNE BELL: Well, again, it depends on where you’re using it. The test itself is– actually executing the test is usually fairly quick. But all the other things that go with analyzing a case in quality assurance and that, that’s where the time comes in.

IRA FLATOW: Dr. Belle, do you agree?

SUZANNE BELL: That was me.

IRA FLATOW: I’m sorry. DesPortes.

BETTY LAYNE DESPORTES: Actually, what I would add to it is that the criminal justice system does not move that quickly. Unfortunately, there are backlogs at our crime labs that keep things from progressing quickly. And then it can be weeks or months before you even get any test results in a case.

IRA FLATOW: Let’s talk about a general lack of science in some big areas of forensic science. Let’s go through some of these– for example, like bite marks. How good are bite marks, Dr. Bell, for evidence?

SUZANNE BELL: Well, I think they’ve been pretty well discredited to this point. The science or the underlying assumptions of bite-mark analysis was that A, human dentition is unique, and B, that when you make those marks in skin, the skin will reflect that uniqueness. And both of those have been pretty well disproven. It’s a subjective method.

And I would urge your readers to look at the PCAST report, which was done last year out of the White House, where they can look at that. It was quite well summarized. So, really, the underlying assumptions of that don’t hold up.

IRA FLATOW: How about hair and ballistics and fingerprinting– the stuff that we always take for granted?

SUZANNE BELL: Things vary across the different disciplines. You can– for example, latent fingerprints has been used for a very long time. A lot of work has been done on– particularly, excellent work done recently on working with fingerprints.

And, you know, it’s worth explaining and emphasizing that these disciplines are– they come from a variety of different heritages. There’s, for example, DNA analysis in forensic chemistry, which I work in– really grew out of science and then was applied forensically, whereas disciplines like firearm, tool marks, latent prints were developed principally in the law enforcement arena. Doesn’t mean they’re not valid, but they really have a different heritage to them.

IRA FLATOW: Dr. DesPortes, I want to go back to that FBI admission in 2015– that for decades, investigators had overstated the accuracy of their hair samples– and, I mean, 95% of the time– in a way that benefited the prosecution. Is this a form of cognitive bias coming into the picture?

BETTY LAYNE DESPORTES: It is. And it explores– it shows that circular kind of validation that has happened with some of these pattern-matching disciplines that grew up within law enforcement, like Dr. Bell was talking about. It’s where law enforcement uses something to identify a suspect and then later uses the same technique in convicting a suspect. They consider that to be validation. They got it right. See? We found the right person.

And, unfortunately, that sort of circular validation also made them very committed to the discipline. And so you would have overstatements along the lines of, well, I’ve never seen in my X years of experience that two hairs would be this similar, so it must be a match. And then they just start making statistics up based on, well, I’ve had, you know, 100 cases in my practice, and there have been 1,000 cases in my lab. And nobody else has ever reported similar hairs like this. So let’s just start throwing in 100,000 as a statistic. One in 100,000. And that’s where the misstatements came in.

And the difficulty is that– because law enforcement has relied on these disciplines for so long, and they believe in them– that it’s very difficult when you have a study that’s criticizing the technique for them to appreciate it. It goes back to that old saying of, it infuriates me to be wrong, when I know I’m right.

And so they have a deep-seated belief in these techniques, and it’s very difficult for them to appreciate the fact that, because they did not arise in science– like DNA and some of the other chemistry disciplines did– that these techniques lack some of the validation studies necessary to prove their worth and their reliability.

IRA FLATOW: So what you’re saying is, no one has really actually carried out tests to test whether these things really are reliable over and over again.

BETTY LAYNE DESPORTES: Correct. As the PCAST report indicated, there have been a lack of empirical studies, the type of studies that show that the analysts, when they do these techniques, are getting the right answer in many of these disciplines. And so we need to have this research done. And for that we need funding. We also need the cooperation of the broader scientific community.

IRA FLATOW: Dr. Bell, what was the National Commission on Forensic Science, which Jeff Sessions has allowed to expire last month?

SUZANNE BELL: It was a group formed in 2013, and we started meeting in 2014. Our charter was to make recommendations to the attorney general regarding forensic science so the audience that we could speak directly to was Department of Justice. But it was a larger scale, in that we hoped that we could make statements and render opinions that could be adopted across the forensic community.

It was a very eclectic group. It was the first time, really, in memory where we’ve had groups from the Innocence Project, prosecutors, public defenders. We had representatives for federal laboratories. We had independent scientists and representatives across the board, laboratory directors in the room at the same time. So it was a very interesting group in that sense.

It took us awhile to get to know each other, but we came to consensus on a number of different documents and recommendations over the long term that affected testimony, practice, scientific foundational terms, and things like that. So it was primarily making recommendations on policy but speaking to the broader community.

IRA FLATOW: 844-724-8255 is our number. Let’s go to the John in North Carolina. Hi, John.

JOHN: Hey, how are you doing?

IRA FLATOW: Hey, there. Go ahead.

JOHN: I was just calling to say that, first, thanks for taking my call. And I enjoy your show when I can catch it. But I’ve been a police officer for 22 years. I’m a detective with my agency, and I do not support this move to cancel the oversight committee on the forensic science. I think it’s just– it’s dumb. We need to have evidence that can stand up in court and passes the “proof beyond a reasonable doubt” threshold. And I do not support Attorney General Sessions disbanding the oversight committee.

IRA FLATOW: Thanks for your call. Any reaction from my guests?

SUZANNE BELL: It’s wonderful to hear that– yeah.

BETTY LAYNE DESPORTES: The Academy certainly– the American Academy of Forensic Science– certainly supports the continuation of the National Commission on Forensic Science.

SUZANNE BELL: Yeah, and– I’m sorry. I was just going to add that it’s really good to hear that, particularly from law-enforcement personnel because it’s not– you know, this is an area where we want to move forward. And we need cooperation from all parties, from law enforcement on up. And it’s great to hear.

IRA FLATOW: And Betty Layne– I’m sorry. I didn’t mean to interrupt you.

SUZANNE BELL: No, just go ahead.

IRA FLATOW: Betty Layne, have you actually seen cases– do you know of bad science affecting criminal cases?

BETTY LAYNE DESPORTES: Sure. And there are many instances that you can see in the newspaper. One that is very well known here in Virginia, which is where I’m from, is the Sofia Silva Lisk sisters case. And that was one where fiber evidence was used to indicate an original suspect after the Silva young girl was killed. And the defendant in that case asked for an expert. He was indigent– couldn’t afford to hire his own– asked the court to appoint an expert.

And the court said, well, you haven’t told me that anything that the Virginia lab did was wrong. So how can– why should I give you an expert? And that’s the real difficult standard that an indigent defendant has.

Unfortunately, two other girls were then kidnapped and killed, the Lisk sisters. And because it was a cross-jurisdiction case, the FBI got involved, did sophisticated DNA testing, determined the two cases were related, seized all the evidence, and found out that, in fact, the fiber evidence did not match. And it was only by that testing that the defendant, the original man charged with Sofia Silva’s case, was released.

And that was a difficulty that you have with indigent defendants is, convincing the court that scientific evidence from a crime lab should be questioned and additional testing should be done. And that’s the difficulty.

IRA FLATOW: Is that because you would have to pay to bring on your own experts to say that?

BETTY LAYNE DESPORTES: Yes. And, unfortunately, in a lot of states, the standard for an indigent defendant trying to get expert assistance from the court– you have to, essentially, have an expert to show why you need an expert. And it’s very, very difficult.

IRA FLATOW: So it’s not– despite all the research that we’re hearing about in the papers and the reports, you still can’t point to those things and say that? You need to spend money bring experts on. And, of course, I guess you’d have to hire researchers to do that also.

BETTY LAYNE DESPORTES: Yeah, it’s a very difficult situation for indigent defendants, where you have to ask for the court to appoint someone, and the court needs justification for expending these funds. It’s different for the prosecution, where they can just send items down to a state crime lab and have it tested. So it is very difficult.

And, unfortunately, courts tend not to rely on newspaper articles or explaining, you know, these reports. They want to know specifically in this case, what can you point to to tell me that this evidence somehow may not be– the conclusions may be wrong? And there, again, you need an expert to show why you need an expert.

IRA FLATOW: Let me just break in here and remind everybody that this is Science Friday from PRI, Public Radio International. Go ahead, Suzanne.

SUZANNE BELL: I was going to say, that’s one of the things I think folks don’t always appreciate– is that you see on TV where suspects get the Miranda warnings– you have the right to an attorney, if you can afford one or not. But you don’t have the same right to scientific review.

And when you consider that most cases now are settled by plea bargaining– very few cases ever go to jury. There’s no more Perry Mason moments. That very often, these folks don’t have the opportunity to talk to other experts.

And a lot of what the service work I do is simply to review cases and talk to defense attorneys and say, this is what it means. This is what they’re saying. And it’s very straightforward. But that’s– I think is something that should be addressed and something we had been discussing in the Commission.

IRA FLATOW: Let me go to the phones. Let’s go to Win in Durham, North Carolina. Hi, Win.

WIN: Hey, I love your show. Love your show. But more to the point, I’m a retired attorney. We just had this fairly large scandal in the last few years in North Carolina where the crime lab just came up with, you know, bogus results to get convictions. I mean, it was run in a dishonest unethical way. So you can clean up the science all you want, but if you have dishonest people running labs, it doesn’t help much.

And more to the doctor’s point, if you’re a wealthy criminal defendant, you can possibly have your own stuff done to double-check to see if the same result is had. But if you’re an indigent defendant, you’re basically out of luck, and you’re going to spend time in jail as an innocent person, as we’ve seen in a lot of cases in North Carolina, where convictions were thrown out.

IRA FLATOW: All right, thanks.

WIN: Thanks a lot.

IRA FLATOW: You’re welcome. Yes, it’s another case of having the money to defend yourself.

SUZANNE BELL: One of the things– go ahead, I’m sorry. I was going to say, one of the things that came up in the National Academy report was a recommendation for a federal-level agency that would be responsible forensic science, where it would be independent from both prosecution and defense. And I think that’s something that’s important and should be considered because that’s– I think forensic science needs a champion that is independent– scientifically independent.

IRA FLATOW: Betty Layne?

BETTY LAYNE DESPORTES: I’d like to point out that there have been some advances, and that there are moves towards more laboratory accreditation and certification of analysts. And that helps to improve the quality of the work coming out of a laboratory. It does not, by all means, solve all the problems. Because if you have a bad actor, it’s difficult to detect. But quality assurance programs give you that type of oversight to where you can catch these problems sooner, and you do not have that type of malfeasance in a laboratory.

And I think that, with accreditation and with certification, that it is a step in the right direction. I do think, however, we do need more oversight and, as Dr. Bell was saying, a champion for forensic science to ensure that there’s adequate funding for all of these measures.

IRA FLATOW: OK, we’re going to have to leave it there and get back to it and talk about this again in the future like we did in 2015. Dr. Suzanne Bell, professor of forensic and analytic chemistry at West Virginia University in Morgantown. Betty Layne DesPortes, president of the American Academy for Forensic Sciences and a criminal defense attorney in Richmond, Virginia.

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