© 2024 WKNO FM
Play Live Radio
Next Up:
0:00 0:00
Available On Air Stations

Analysing The Evidence On DNA


This is SCIENCE FRIDAY, I'm Ira Flatow. We're here in Boise, Idaho, talking, broadcasting from the campus of Boise State University, and we're going to talk about the use and abuse of DNA evidence, excuse me. Forensic techniques to investigate crime scenes have been coming under increasing scrutiny.

Questions have been raised about fingerprint interpretation, blood-spatter analysis, bite-mark and fiber analysis, but DNA, DNA has been held up as a gold standard in forensics. DNA found at the crime scene matches the suspects? Case closed most of the time.

But my first guest says we should be taking a closer look at how we use DNA. Not all DNA evidence is created equal. Sampling techniques are changing, so the standards for using DNA evidence should be changing, too, he says.

Greg Hampikian is director of the Idaho Innocence Project and a professor in the Department of Biological Sciences and Criminal Justice here at Boise State University. Welcome to the program.

GREG HAMPIKIAN: Thanks very much.

FLATOW: Walk us how through DNA evidence is collected at the scene of a crime.

HAMPIKIAN: Well, that's changing, but, you know, in a lot of our rural communities, it hasn't changed much at all in 20 years, probably. So you don't always have a CSI team and booties and...

FLATOW: It's not like on television, in other words.

HAMPIKIAN: Not most times. And so that makes it difficult because you collect more than you want. You often collect spurious items. There's a lot of vacuum-cleaner bags full of hairs that I've gone through in cases. And the sensitivity has increased. When I was in grad school, we'd deal with a microgram of DNA. We now use picograms. So that's a million-fold, almost single-molecule resolution now.

And unfortunately we're collecting much as we have for many, many years. So I think the sensitivity problem is a big issue.

FLATOW: So that means that you're finding DNA at a crime scene that may have nothing to do with the crime.

HAMPIKIAN: Exactly, exactly.

FLATOW: But it's being used to place people who might not be there at the crime.

HAMPIKIAN: Well, I mean, Amanda Knox' case is a good example.

FLATOW: Let's talk about that.

HAMPIKIAN: Yeah, I worked on that case here at Boise State and also in Italy, and we showed in my laboratory that if we followed the practices that we saw on the videotapes during the collection of evidence that you would get transfer, that you would get transfer specifically to a knife from dirty gloves. And that may have been the evidence that was used to implicate Amanda in the beginning.

Fortunately, Italian experts appointed by the judge agreed absolutely with our findings and said that that was probably contamination.

FLATOW: So DNA could accidentally wind up at the crime scene is what you're saying, unintended, and be used against the accused.

HAMPIKIAN: I mean, I had another case, I gave my students this great math problem. We had a case where there was one sperm cell that was found on some underclothing of a very young person, and there was an accusation against a father in this case. And the question was: How probative is it to find one sperm cell?

So I gave them this problem. It was summertime. And I said, you know, I swim in the public pools. Let's say someone goes into an Olympic-sized swimming pool with one ejaculate on them or in them or whatever, and it gets washed off. And how many gallons of water do you have to go through before you hit one of those sperm cells?

It's a very easy problem. People - you can take out a pencil and do this yourself, 300,000 gallons in an Olympic-size swimming pool, 300 million cells in an average ejaculate. That's 1,000 cells per gallon for every ejaculate every summer.

So these numbers that we're now doing, in the old days - I hope I'm not getting censored with my terminology.


FLATOW: No, we're very clinical. We're being very clinical.

HAMPIKIAN: You should come to dinner at my house.


HAMPIKIAN: Maybe not. But so I mean, the fact is that years ago, we wouldn't have detected one cell. We wouldn't have detected 50 cells, 1,000 cells. We needed a million cells when I was in graduate school. Now my lab detects routinely 20 to 40 cells, and we don't even look at that level. We always go above that to start our analysis.

FLATOW: Right, well, doesn't that make it easy, then, for a defense attorney to say, you know, it could have come from anywhere, any time?

HAMPIKIAN: I think you can say that. I don't think you have much luck most of the time because people talk about the "CSI" effect, and it's real, and it's good because juries listen to experts now very carefully, and that's good. The bad thing is DNA has this aura that people don't know how to criticize.

So things like sensitivity, and then we published recently, (unintelligible) and myself, about mixture analysis, which is even worse.

FLATOW: 1-800-989-8255 is our number. We're not taking phone calls this hour, but we are taking people in the audience. If you have a question here in the audience, you'd like to ask about DNA findings and analysis, please step up to the microphone.

So what's your recommendation about how DNA then should be handled and analyzed and used in crime scenes?

HAMPIKIAN: Well, more training, from the ground up. So we're doing a training here in Idaho. We're starting with police officers in Ada County to look at identification, and from there we're going to DNA collection. So I think training's very important and also educating the public like you're doing. I think there's a difference that they need to know. Any fifth-grader I could teach to interpret a DNA stain when there's on contributor, very easy to compare a stain to a known.

When you have a mixture, it's like taking Scrabble tiles for your name and my name. You put two people in a bowl, let's say, and you can pull 1,000 names out, and that's what mixture analysis is like. It's complex. It's very easy to say somebody cannot be excluded. I have a case like that in Georgia right now.

FLATOW: How much training do we have to - do we have to retrain, then, all of our law enforcement people?

HAMPIKIAN: Absolutely, yeah, you have to retrain, and you have to start with the trainers, because the people who are training officers are not up to date on a lot of the most modern technology. I mean, that's asking a lot, and it's not easy to do.

FLATOW: Let me see if we can get a question here from the audience.

UNIDENTIFIED MAN: I'd like to know how - can you give us a sense of how often DNA is used in trials and in investigations?

HAMPIKIAN: So, I mean, my experience is limited to, you know, rape and homicide, pretty much. And it's frequently used in rape cases. There's a collection kit that's used every time there's a sexual assault. And certainly the lab will try to get DNA every time there's a sexual assault from those kits. How often that's successful I'm not sure, but I'd say, you know, a quarter of the time, off the top of my head, it's successful.

Same thing with homicides. My bicycle was stolen here in Atlanta, and the police brought it back to me, and there was a knife in my bag, and I picked it up with gloves and said: Do you want me to swab this? They don't do property crime here yet, but other police agencies are starting to do that. It's not expensive, and it's easy to do and very probative.

FLATOW: Should - thanks for the question. The police have a vested interest in the case, right?

HAMPIKIAN: Solving crime?

FLATOW: Solving crime, right.

HAMPIKIAN: That's their job.


HAMPIKIAN: They're very interested, I'm sure.

FLATOW: They would like to solve the crime. Should they be separate, then, from the testing of the DNA?

HAMPIKIAN: That's a question - you know, the National Academy of Sciences came up with this before I did, you know, or - and says that of course you want independence. Some of my friends who work in crime labs, very good scientists, have badges. And when you go into court, and they're good friends with the district attorney, and they're good friends with the officers, and they see these people at functions, and they're all paid by the same entity, I think I would have a little bit of bias.

And so some states have separated them. I think it works out better.

FLATOW: Let's see if we can go to the audience and get a question here. Yes, sir.

UNIDENTIFIED MAN: Yes, are more rapists using condoms now to avoid DNA detection?

HAMPIKIAN: You know, I haven't seen a study done, but anecdotally, as an anecdote, the officers that I work with tell me yes. Some of them are using other methods that are, you know, even worse in terms of getting rid of evidence and, I mean, actually damage people, hurt the victims.

And we had one case here in Idaho where somebody raped a woman, was completely bald, had shaved the hair off their body and collected the sheets when they left. So some of the criminals are watching the "CSI" shows. I'm not giving away any secrets here. Yeah, people are wizening up, and some of those people are committing crimes.

FLATOW: More like "Dexter."


FLATOW: Yes, ma'am.

UNIDENTIFIED WOMAN: So speaking of the "CSI" effect, how long does it really take to do the analysis? You know, on television I think it's about 15 to 20 minutes.


HAMPIKIAN: Well, so here at Boise State, we're developing - we're in a race with a bunch of other places, trying to develop a one-hour DNA analysis kit, remote analysis kit. In material science, Peter Moeller's(ph) group and I worked on a miniature pump for one of these, and also in materials science we worked on a miniature PCR device.

So I think the best competition is down to four hours right now, but when people ask me to rush a job, I give them a careful estimate, multiple by pi and tell them about a week.


FLATOW: You have an idea for adding a marker to a DNA sample so that once a sample is collected by the police, the blood couldn't end up somewhere else and contaminate a different sample.

HAMPIKIAN: Yeah, this is a really fun project. So we, in my lab, kind of pioneered this idea of looking at sequences that don't exist in nature - DNA and protein. We have a paper in the journal Peptides, next issue, where we show that these sequences are, what we hoped, killers and can kill cancer cells. So we have a paper coming out on that.

And the other thing that we're doing is taking DNA that doesn't exist in nature and making like watermarks that you can put to the sample. So let's say you're asked, because you're a victim or a suspect, to give a sample to the police. You give a cheek sample, it's with a Q-tip. How do you know it doesn't get spilled in the lab, on the way, whatever?

We're talking a few molecules spill. And we've here in my lab developed a marker that we can put into the sample, and even if it's diluted a million times, it shows this is a reference sample.

FLATOW: You mean as it's collected, you would put it in...?

HAMPIKIAN: Yeah, and in fact, you know, I have a patent going forward. We have a paper that I hope is ready to be published next month.

FLATOW: Quick question from the audience.

UNIDENTIFIED MAN: OK, you know, you hear about these cases where people were put into jail 20 years ago on DNA, and then they re-examine it today, and then they find out oh, there was a mistake here, wrong person or something to that effect. So my question is: Is there an expiration date on DNA samples? And what do you think about that?

HAMPIKIAN: Well, let's see, in amber, the expiration is somewhere beyond 60 million years. And, you know, the enemies of DNA are moisture. So if you save evidence, don't stick it in the plastic bag, dry it thoroughly, and you can do this. I've received evidence from students who were collecting evidence on things like Q-tips, toothbrushes, you know, a clean tampon that was used that we're processing right now.

So it has a really good life if you keep it dry and out of the sunlight. Those are the two chief enemies. But room temperature is fine, and just keep it dry. You can put it in the freezer if you want, and it has a very good shelf life.

FLATOW: Thank you, Dr. Hampikian. We've run out of time. Thank you very much, quite interesting. Greg Hampikian is director of the Idaho Innocence Project, professor in the Department of Biological Sciences Criminal Justice here at the Boise State University.

We're going to take a break, and we're going to talk about the American West under siege by fires and an invasive weed and how they are connected. And we're going to talk about how they're changing the landscape of the open range. Stay with us. We'll be right back after this break.



FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR. Transcript provided by NPR, Copyright NPR.