Law and the Genetics of Identity: The Science of DNA Fingerprinting

We've heard a lot about DNA forensics in the news — the process of testing DNA, finding DNA matches, and creating DNA profiles of individuals makes for great headlines. But what exactly is DNA forensics, and how does it work?

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The DNA Files: Unraveling the Mysteries of Genetics

“Law and The Genetics of Identity”

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“Law and The Genetics of Identity”

JOHN HOCKENBERRY: This is The DNA Files, I’m John Hockenberry.
Imagine being convicted of a crime you didn’t commit

JOHN HOCKENBERRY: Imagine, while in jail, trying to find new evidence to prove your innocence.

[Tape]: A lot of the people we deal with are the ghosts. They're these ghosts haunting the prisons of America, who are factually innocent, and have been unjustly convicted and they keep pleading their case and every time they plead it, it falls on deaf ears.

JOHN HOCKENBERRY: DNA testing is used to exonerate, convict, and locate criminals. The same tests are used to establish paternity, find missing children and identify plane crash victims. We leave our DNA everywhere we go, and someday that might help you or harm you. Coming up, a DNA Files Who Done It?

But First.....

Will the 1990's be remembered as the Age of Exhumation, when suddenly the famous dead no longer rested easily? The French unburied a cultural icon, singer Yves Montand, because of a paternity suit; the Russians reburied the last Czar, 80 years after the Bolshevik Revolution, and the United States removed one soldier from the Tomb of the Unknowns, all because of a technology that none of them lived to see. Forensic scientists have learned to read the DNA of the dead. John Rieger has these Notes from Underground.

[Harmonica music & digging noise]

It sounds like an old howler. Who’s buried in Jesse James’ grave?

MALE VOICE: [laughter] We bury ‘em deep.”

JOHN RIEGER: But descendants of the famous outlaw aren’t laughing. And the histories aren’t helping.

JAMES STARRS: I’m a great believer in Voltaire’s statement that God in all of his omnipotence could not change the past and that’s why he created historians.

JOHN RIEGER: Standing in an open grave with a professorial air and an impeccable white beard is James Starrs, professor of law and forensics and George Washington University. In his off hours Starrs’ special passion is to correct the caprices of historians by unburying the dead and famous.

JAMES STARRS: That is a piece of bone.

[male voice respondent - “Yeah, that’s a piece of skull.”]

JAMES STARRS: As far as I am concerned and the individual members of my team, there is no lack of certainty that we have identified the remains as being those of Jesse James. The hair, and the teeth and the known relatives all matched uh to a T, or to a uh...a TGAC.

JOHN RIEGER: T G A & C, of course, are the four building blocks called nuclei tides which make up the genetic code in DNA. Forensics is the science of legal evidence and DNA analysis is a powerful new tool for establishing the identity of the dead. Professor Starrs, a crusader for all the latest techniques, has set out to promote them with a series of demonstration projects.

JAMES STARRS: I decided literally to go public, and I felt the best way to go public was to take on historical cases, and I started, of course, with the best of the lot with Alfred Packer, the Colorado Cannibal charged with...with cannibalizing five of his prospector friends in the high mountains of the San Juans in Colorado.

JOHN RIEGER: Starrs has a noted gift for publicity, perhaps befitting a crusader. He dug up Alfred Packer. He dug up Jesse James. He’s raised pointed question about the lack of an autopsy for J. Edgar Hoover. And now, he’s questioning the death of one of America’s greatest explorers, Merriwether Lewis, of Lewis and Clarke, who died in 1809 a suicide...or was it?

JAMES STARRS: Merriwether Lewis is supposed to have shot himself twice with a very large caliber flintlock muzzle loading black powder weapon. Merriwether Lewis was a skilled marksman. Why did it take two shots and indeed, uh there were those who say that two shots didn’t even do the job. That he ended up by having to hack away at himself with a razor blade. That just doesn’t measure up to scientific truth.

CONSTANCE ELLIOTT: I am Constance Elliott, one of Merriwether Lewis’ closest relatives. My mother and father were about fifth cousins, and each one was related to Merriwether Lewis.

JOHN RIEGER: Constance Elliott, 80 years old, lives in rural Virginia. Her cells hold the key to step one, identifying the body. Men and women both have a form of DNA called mitochondrial DNA which comes only from their mothers. Sons don’t pass it along - daughters do. Merriwether Lewis and his sister Jane got their mitochondrial DNA from their mother. Constance Elliott descended from Jane through a line of women, has the same mitochondrial DNA. So, the remains of Merriwether Lewis can be positively identified by matching Constance Elliott’s DNA with his. One just has to dig him up.

CONSTANCE ELLIOTT: I don’t have any particular feeling about disturbing a grave. Uh......have you driven from New Jersey into New York City? Well, look to your left and your right and you’ll see graves. The road goes right through them.

JOHN RIEGER: But how will the dead ever rest now that we can summon their testimony from the grave? For James Starrs the new technology isn’t about questions for the dead but answers for the living.

JAMES STARRS: It’s quite clear that the relatives of a great man and a great explorer, that these relatives have carried over many generations the stigma of the suicide of Merriwether Lewis and they don’t want it necessarily to be proved that it’s something other than suicide such as homicide. They just want to know the truth.

JOHN RIEGER: For The DNA Files, I’m John Rieger.

JOHN HOCKENBERRY: I’m John Hockenberry: Welcome to The DNA Files. Today on the program we’re going to take a look at DNA forensics: that is, DNA and the law, DNA testing, DNA profiles, DNA matches - we’ve heard these words a lot in recent times. There was the OJ Simpson trial, you recall, and lately that blue cocktail dress. We’ve heard a lot, but how much we do really understand? How are those DNA tests done? What do they mean? What can they be used for, and what are the social and ethical implications for the future? There ‘s lot of questions-

MAITRE’D: Bonjour monsieur. So good to see you. Welcome to the Cafe DNA.

JOHN HOCKENBERRY: -which is why I’ve brought you here... to the Cafe DNA. This is one of the trendier restaurants in town right now. All the big shots in the world of DNA forensics turn up here....lawyers, scientists, media types, all sorts of people-

MAITRE’D: Pardon, but does monsieur have a reservation?

JOHN HOCKENBERRY: No, I’m afraid I don’t. Is that going to be a problem?

MAITRE’D: What a pity. It seems we have no table for you.

JOHN HOCKENBERRY: OK, I didn’t really want to sit down. I think I’ll just wander around the room, if you don’t mind, and see who’s here... (aside) Just between you and me, the food’s not that great here. At the DNA cafe they only serve genetically engineered stuff: tomatoes in the shape of the Parthanon..... broccoli laced with growth hormone..... and something called the “catch of the day,” which is a cross between a duck and a mosquito. But you don’t come here to eat. The idea is to move around , check out the crowd, and.... let’s face it.....eavesdrop. So let’s see.....Let’s see. Oh. Look over there... You,you see the gentleman back in the corner? That’s Alec Jeffries. He’s a Brit. Sir Alec Jeffries, in fact, quite famous. He’s a geneticist at the University of Leiscester, and he’s know as the father of DNA testing, or DNA profiling. He was the first person to use it in a real criminal investigation. It was in the mid ‘80s, in England....

ALEC JEFFRIES: This was tragic case, local to Leiscester where I live, of two young schoolgirls, both of who had been raped and murdered, one in 1983, and one in 1986. Now, shortly after the second murder a young man was arrested, in front of his lawyer, fully confessed to the second murder to the police, but denied any knowledge of the first murder. Now, the patterns of the murders were so similar, even though they occurred three years apart, so that the police were fairly convinced that whoever carried out the second murder had carried out the first as well. Yet this young man was denying any knowledge of the first murder. So we thought, let’s take this DNA profiling, and uh let’s have courage in the technology, and see if we can carry out an investigation. Which we did, and led to really quite a startling result. First of all, beyond any reasonable doubts, the police were right that both victims had been raped- and therefore presumably murdered- by the same man. But secondly-- and this is where I began to doubt my own technology,--there was a complete genetic mismatch between those semen samples and this prime suspect who’d already confessed to one of the two murders. The police then released this young man, and he now stands as the first person ever in the world to be proved innocent by DNA analysis.

JOHN HOCKENBERRY: Sir Jeffries is making a good point there, you know. Usually we think of people being convicted by DNA evidence. But it can just as well establish innocence......As a matter of fact I see a man on the other side of the room now who’s one of the one of the founders of something called The Innocence Project. That’s very interesting. We’ll go over there in minute. First let’s hear how Jeffries’ story turns out. Here they are, they’ve discovered they’ve got the wrong man, and now they’ve had to let him go:

ALEC JEFFRIES: The police then took what I think was an incredibly brave decision: and that is not to disbelieve in this science, but to actually believe in it whole-heartedly, and to launch the world’s first DNA-based manhunt. The idea very simply was to scour the entire local community asking for people to come forward on a voluntary basis to give blood samples, and then to check the genetic profile of the blood samples to see if they could eliminate everybody, and eventually whittle their list of possible suspects down to one man, the true offender. Now, 5,811men were approached, and I think there was only one person who refused , and I think that was on religious grounds. He certainly wasn’t the guilty party. The true assailant almost got away with it. And what he did was to go around to his friends asking if anybody would be prepared to stand in as a substitute for him. And he eventually uh found a friend of his who said, “yes I’ll do that.” The argument he put forward was that he did have a previous record of offenses, and he was worried that the police were going to frame him or stitch him up. They then hatched this plot, whereby the friend would go along with this person’s passport, and the blood sample was duly given by the substitute, and the true assailant some time later received a letter from the police clearing him from the investigation. And at that point the trail went cold. It would have gone cold forever were it not for the fact that the man who’d acted as a substitute was in a pub one evening, was talking to uh colleagues, and [unintelligible word] in the conversation happened to let slip that he stood in as a substitute. A woman sitting at a table nearby happened to overhear the conversation , uh went home, started worrying about it, and sometime later then went to police. The police then brought this man, found out that the other man who’d avoided giving the proper blood sample was a man by the name of Colin Pitchfork. His profession was a cake decorator---- not a profession one normally associates with serial killing. I believe he actually confessed to the murders on the spot. He was DNA typed and everything matched.

JOHN HOCKENBERRY: Hmmmm.....There you have it, convicted by DNA. Of course, keep in mind you could just as well be proved innocent with genetic evidence. Let’s go over and meet Peter Neufeuld. He’s a lawyer, but five or six years ago, he helped start a free legal clinic known as the Innocence Project. It operates out of the Cordozo School of Law at Yeshiva University in New York. The idea is to use DNA to free people who’ve been convicted unjustly. Sometimes Neufeld and his colleagues can find genetic evidence that wasn’t know, or wasn’t used, at the original trial.

PETER NEUFELD: Well, when you talk about consequences of the Innocence Project, to date there have been about 58 people nationwide exonerated post conviction through the use of DNA testing.

JOHN HOCKENBERRY:And let’s just to say to clarify that these exonerations came by submitting your DNA evidence not to a jury but to a judge, correct?

PETER NEUFELD: Actually, in many of the instances we don’t even get to a judge. In ninety percent of the states there is very strict statute of limitations permitting you to go back into court with newly discovered evidence such as our DNA exonerations. 41 out of the 50 states have very strict limits. So if you get this new evidence six months later or a year after conviction, you are barred from going back into court. And your only relief is to go before a governor and seek a pardon or clemency.

JOHN HOCKENBERRY: You’ve encountered convicts, people who presume that they would never be leaving prison who you walked up to and said, “you know I think I can prove that you’re innocent.”

PETER NEUFELD: You know a lot of the people we deal with are the are the ghosts. They’re are these ghosts haunting the prisons of America, who are factually innocent and have been unjustly convicted, and they keep pleading their cases and uh every time they plead it falls on deaf ears. We approach them, we say we can actually do something. Many of these people have given up all hope. Some of them have been in prison as long as 20 years. Approximately a dozen of the people who have been exonerated were in fact on death row and their appeals have been exhausted. So there’s a mixture of pessimism and cynicism on their part; yet somewhere in the back of their character they are holding out some degree of hope that this is the light at the end of the tunnel, and there is that ambivalence. But what’s extraordinary is when we get the results. And I can tell you that there is no moment that we’ve experienced as law students or lawyers that comes close to that, when you can get to that prison, and reach out to that client and open the prison doors and allow that man come out outside into sun. It’s the most rewarding feeling I’ve ever experienced as an attorney.

JOHN HOCKENBERRY: Who, who’ve you managed to free is a most satisfying success for you?

PETER NEUFELD: It’s too soon to say what’s satisfying. You have to remember that all of these people carry the scars of imprisonment. And I can’t think of anything worse than being in prison when you know you’re actually innocent. And so, all of these people have, to a certain extent suffered permanent psychological impairment as a result of their unjust incarcerations. And for every one of these uh men and women, they take one day at a time to try and work their lives out.. There was one man in particular, the day he was released he walked down a street and there was no one on the street in a small residential community, and he kept looking over his shoulder because he had been experiencing so frequently uh gang warfare, that even when there was no one within blocks of him, he was convinced that somebody would be there with a shiv or some other makeshift weapon to cause him bodily harm. And it took it days if not weeks before he stopped doing that.

JOHN HOCKENBERRY: We’ve been talking with Peter Neufeld, from the Innocence Project. Now....let’s walk around the caf» some more, see who else is here. There’s a couple over there I don’t recognize. Looks like they’re having an extremely intense conversation. (whispered) Let’s just sort of ....edge over a little closer so we can....hear what’s going on

LARRY MASSETT: Oops. Uh uh I’m sorry.

ALICE: Oh. Oh. That’s OK. That’s OK.

LARRY MASSETT: No, I, no, I can get a napkin.

ALICE: It’s really it’s OK. But, but you you didn’t actually DO that, did you? How COULD you, a, a crime like that? It’s so unspeakable

LARRY MASSETT: Yeah I know. I know. Well, at first I didn’t think I did it. I mean it’s hard to see how I could have broken into my neighbor’s house in the middle of the night with a copy of Vogue Magazine in one hand and a hamster in the other and then -in cold blood-

ALICE: Please, let’s not go over the details again. I-I’m trying to eat .

LARRY MASSETT: OK. Yeah. You’re right, you’re right. It’s, it’s just unspeakable. It’s disgusting. But see the thing is, I wasn’t SURE I hadn’t done it. I mean I happen to have a very bad memory.

ALICE: You do? What ‘s my name?


ALICE: OK. Your memory’s not too bad. But didn’t you say there were eye-witnesses who saw you coming out of the house?

LARRY MASSETT: Well, yeah. But you know, so what? I mean it was dark. I’m an ordinary-looking guy. It was an ordinary looking hamster. And anyway uh you know my friend Barney, who’s on the police force? Barney tells me that eyewitnesses get things wrong all the time.


LARRY MASSETT: It’s no big deal. Now, what DID bother me, though, was when Barney said there were cigarette butts all over the crime scene.

ALICE: Well, so what? Lots of people smoke....well, anyway there must be a few other people in America who still smoke.

LARRY MASSETT: Yeah. Yeah, but Barney said these were unusual cigarettes. Filters with the brand name Pakistani Red. Happens to be the kind I smoke.

ALICE: Well, circumstantial, that doesn’t prove a thing. If it were me, I’d go on vacation and wait to see if the cops file a charge.

LARRY MASSETT: No. No, I felt like I had to know. I-I really wanted to know. Good old Barney- we’re pals- he slips me one of the cigarette butts the cops found. I mean, you know, why not? They’ve got lots of them. I figure I can take the one and go have a DNA test.

ALICE: Just so you could find out?

LARRY MASSETT: Yeah, right. I go and I get my blood sampled and then I take the cigarette, and the blood in the little test-tube, and I go to a laboratory that does DNA forensic tests.

ALICE: Well, what a good idea.....I suppose...

MARK STOLLEROE: My name is Mark Stolleroe. I’m director of operations at Cellmark Diagnostics in Germantown, Maryland. Um we’re now in the laboratory where the majority of DNA testing at Cellmark Diagnostics is performed. This room is about 30 by 30, and it contains 6 independent lab-bench islands, that will provide laboratory area, workspace, for about a dozen scientists. That’s our autoclave. The purpose of having an autoclave in a laboratory like this is to sterilize the samples before they’re used. And we have our instruments, glassware, and disposable tubes that we put DNA in, go through an autoclave first to insure that there is no contamination...

LARRY MASSETT: It actually looks uh-looks a little bit like a, well, like your high-school chemistry lab, if you had a very well stocked chemistry lab. It’s about like that. It isn’t really all that Frankenstein- looking..... What’s the first thing that you do now?

MARK STOLLEROE: Once these samples have been received, we record the condition of the packages that are sent to us in order to begin what we call the “chain of custody”. The “chain of custody” is a very critical element to make evidence admissible in a court of law. So we’re very careful to note how the package is sealed when it first arrives, and to record that information. Then we log the information that is on the items that have been submitted. We describe the items. In this case uh we have a cigarette butt, which is going to be described in our notes... and a tube of blood, which has come from someone, for comparison. Here this tube of blood, as you can see, is markings on it from the collector, from the nurse that collected this sample...and that’s the beginning of the chain of custody. The cigarette you can see it’s in kind of a rough condition, and the person who smoked it wasn’t kind enough to initial it for us. So we’re going to try to find the owner of that cigarette butt through the DNA which is deposited on the end here, and you can see this crusty material on the end of the cigarette butt. We hope that’s going to be a rich source of DNA. So now we have all of this evidence laid out on sterile paper and we photograph it, and we photograph it. We use a Polaroid camera here, let me pull this over— and we take pictures so that we can show what the evidence looks like as we receive it, and before any testing or cuttings are made. And as soon as we’re done with our photography and logging in this evidence on our evidence receipt, then we’re ready to start the chemical extraction of DNA and purify this DNA for comparison.

LARRY MASSETT: So, they do all this futzing around, recording every little thing, and it takes forever. Of course, they have to do this, because you know how later on the lawyers might like to sort of hint that that the laboratory has messed up the evidence some way, right. Finally, they get some little tiny scissors and tweezers and they start cutting the paper off the cigarette filter. The cigarette filter is what they’re call the “evidence sample”; and my blood sample is going to be what they call the “ reference sample.”

MARK STOLLEROE: And these cutting are being placed into a plastic conical centrifuge tube that’s open on one end, and as you can see the bottom forms a nice little point. The reason for this cone shape is that we want the DNA eventually to move to the bottom of these little centrifuge tubes and concentrate themselves at the bottom of the tube.. We’re now going to pipette into that tube a few microliters of an extraction chemical, and this is going to enable the cells from the mouth- like cells that line the cheek or the lips—to be broken open, and the membrane of those cells is going to break open with the addition of this solution, and the chromosomes that are inside the nucleus of those cells will go into the solution. So we’ll now we will have the filter paper, the chemical and the DNA dissolved in the solution. We’ll close the cover and then we’re going to place it in another location here in this laboratory in a water bath that is a controlled temperature water bath. In fact, you can see from the temperature it’s the same as body temperature. And we extract the DNA overnight. And then tomorrow morning we’ll evaluate how much DNA is in this extraction.

LARRY MASSETT: Oops. Sorry about that.

ALICE: No. That- that’s OK.

LARRY MASSETT: That’s- you know, that’s bad luck, that’s all.

ALICE: Tomorrow morning, is that what he said? They really can’t do it all in one day?

LARRY MASSETT: Nope . It turns out you’re,you just wait. You’re always waiting. You wait for the chemicals to finish doing their thing, you wait for the film to develop. It’s you know, what one thing or another day after day.

ALICE: I always wondered why it took so long.

LARRY MASSETT: Yeah, well, it just takes uh...

ALICE: Could, can uh I have a bite of that thing on your plate?

LARRY MASSETT: The blue thing?

ALICE: Yeah.

LARRY MASSETT: Yeah. Sure. Go ahead.

ALICE: Thank you.

LARRY MASSETT: Knock yourself out.

ALICE: Anyway, remind me, what is it that the lab is looking for? I mean I know it has to do with DNA, and I know that DNA is like a code, instructions for making proteins in our bodies.

LARRY MASSETT: That’s right.

ALICE: But what is the laboratory after?

LARRY MASSETT: Well, you know how your DNA and my DNA and,and everybody’s DNA is pretty much the same. We’re all human, right? But here’s the thing, there are a few small sections of our DNA where- as it happens- we differ quite a bit. There are these areas on our chromosomes that are not instructions for making proteins. They may not be instructions for anything.

ALICE: Well, what are they doing there ?

LARRY MASSETT: I don’t know.


LARRY MASSETT: Nobody seems to know. They can be handy when it comes to forensics. You know how they tell you that DNA has four building blocks, there are four chemicals which scientists call A, C, T, and G.

ALICE: Yeah I’ve heard that. A, C, T, G it stands for?

LARRY MASSETT: A C T G. It stands for longer chemical names, OK. The important thing is the order in which they run. And that’s the message. That’s the genetic code. It’s,it’s like you have that’s only got four letters, A C T & G. In these peculiar areas that don’t seem to have a message, the A’s and C’s and T’s and G’s just sort of run on and on, and on and on like a bunch of nonsense syllables.

ALICE: (singsong) Mares eat oats and lambs eat oats and little lambs eat ivy.

Please. I’m trying to, I’m trying to eat

ALICE: Oh, I’m, I’m terribly sorry.

LARRY MASSETT: Anyway, it’s, it’s the nonsense that tends to be different from one person to the next. That’s just the way it is.

ALICE: Got it.


ALICE: OK. Now, anyway, you go back to the laboratory the next day...

LARRY MASSETT: Right, I go back and I meet this guy, Mark Stellerore again, there he is.....

MARK STOLLEROE: And you remember yesterday we placed these samples into the water bath.. And as I remove them from the water bath—ooh, they’re nice and warm. And we carefully remove a very small amount- just a few microliters. And I am mixing these with a very small amount of dye- as you can see- to place them into the electrophoresis gel. Electrophoresis is a chemical process to separate molecules based on their charge. And electrophoresis is simply defined as the movement of charged particles through an electric field. That’s a lot of scientific terminology for something which really is nothing more than a 2 by 3 inch piece of jello. This clear, jelly-like material is made of the same type of material extracted from seaweed, called agar. And that’s boiled in a flask and poured as a viscous liquid into this little mold. And this gel forms when the solution cools. And uh you’ll notice we that have a comb with 14 teeth on it. And these teeth simply form a depression in the gel, so that when we pull the comb out, there are 14 holes lined up across the edge of the electrophoresis gel. We will place samples of known DNA extractions in several of these wells as a known marker. And then we’re going to place a small amount of blue- dye-colored extracted DNA from the cigarette butt, in this well, and a small amount of DNA extracted from your blood sample in a well, several wells away from it. And then we’re going to cause electric current to pass through this gel. The red wire, the red terminal, is the positive end, or “anode,” and the black terminal denotes the negative charge, or the “cathode.” And DNA will move toward the red pole, or move toward the positive pole. So now that this is in place, we plug it in, and over the period of the next half an hour or so, we’ll see the blue dye migrate across that gel, indicating that these molecules are moving in the direction that we want them to.

LARRY MASSETT: So there you have it: electrophoresis, which turns out to be jello on a glass plate with a 75 watt current running through it, plus a few tiny drops of DNA on the jello, trying to scurry away from the negative electricity.

MARK STOLLEROE: Now we return to the electrophoresis chambers. And you can see, looking into this chamber, that the blue dye has now moved from the sample wells where the liquid was introduced, to the far end of the gel, indicating that the run has been completed. And now that that’s done, we will turn of the electricity and we’ll disconnect the terminal plugs, and reach into the solution...... and pull out the electrophoresis plate. And this small little plate can now be looked at through ultraviolet light.

LARRY MASSETT: OK. So, we’re going to look at it through ultraviolet light now, is that the idea?

MARK STOLLEROE: Yeah, so, we’ll move over to a trans-illuminator. A trans-illuminator is a fancy word for an ultraviolet light box. Right, so now we place the sample on the trans-illuminator, and uh, the evidence samples, as you can see, stay very near the top of the gel where we introduced them. This is a good sign, because it means the DNA ha not broken down.. The other thing that’s important is that you’ll notice this nice intense bright band. And that means that there is a lot of DNA there, a sufficient amount of DNA for us to do RFLP testing. And this sample is the known reference sample, and it looks like and your DNA is in pretty good shape. So we can move ahead right ahead now with preparing the sample for RFLP DNA analysis. I’m going to shut off the trans-illuminator before we leave

LARRY MASSETT: (sighs) Man, all that just to see if we’re going to START doing the DNA test? I mean all we’ve done so far is establish that there’s enough DNA to begin. These guys have a lot a patience. But wait a minute. What’s an RFLP anyway?

MARK STOLLEROE: There are two different groups of techniques that can be used for DNA testing in a forensic laboratory. The older of the two methods is called RFLP: It stands for “restriction fragment length polymorphism.” And that’s kind of a long term to describe what, in its simplest form, produces DNA patterns that look something like universal product codes, or bar codes. The DNA is broken into fragments with the help of a chemical known as an enzyme. And the fragments are of a unique combination of sizes, based on the unique chemical structure that everyone has in their DNA. So, if your DNA is unique to you, when your DNA is recovered from saliva, or it’s recovered from hair, or skin or blood ..that the fragment pattern for you will always be the same regardless of which tissue or which sample of DNA is taken from you. Your pattern will be different, however, from everyone else. And by comparing these bar codes from each individual, we can tell which samples are matching and which samples are not matching, and therefore could not have originated from the same person. In order for RFLP testing to work in our laboratory, there has to be a sufficient amount. It has to be, for example, from a blood stain about the size of dime, or semen the size of a dime. For saliva, there is enough saliva from a cigarette butt on some occasions for us to successfully do RFLP testing. If the DNA is either too small in quality or if the DNA which is present has degraded, or broken down, then we have to go to the alternative means of DNA testing in our laboratory, which is called PCR. Very basically, P C R, which stands for polymerese chain reaction, is a very simple and elegant duplication in the laboratory of replicating DNA in exactly the same way that living cells replicates its DNA in chromosomes before the cell divides. And that enables the small amounts of DNA, or degraded amounts of DNA, to be multiplied---- something like chemical Xeroxing. And in a matter of a couple hours we can go from a only a few copies of original starting material of DNA to a million fold or billion fold increase of the target DNA , so that it is in sufficient quantity to detect.

LARRY MASSETT: PCR, RFLP... I think I’m starting to get a headache. I may have an allergy to acronyms. But what the heck. We’re almost ready to do the test now. We go back to the original samples. We know we don’t have to do PCR. Remember we’re not interested in the whole DNA. We’re only trying to get at those little fragments that have got the nonsense syllables in them. So, we have to cut up the DNA up to get at the fragments. We’re going to add some chemical scissors- Mark calls them restriction enzymes- and they will do the cutting for us.

MARK STOLLEROE: This is a process that will be conducted overnight. So today is a short day for you. All we have to do is to add the restriction enzyme to these tubes, snap the tubes closed again, put the tubes into this warm water bath, that will keep it warm overnight, and tomorrow morning we will see whether the cutting has been completed successfully.

LARRY MASSETT: There’s a lot of just standing around and waiting involved in this isn’t there?

MARK STOLLEROE: Well, make sure you don’t tell any of our administrators that we have this down time.... They wonder why it takes several weeks rather than a few hours to get their test results.

ALEC JEFFRIES: See at the moment, and again, the OJ Simpson case is a very good case in point, where you have evidence placed at the scene of the crime. It then has to be taken to the laboratory, and then all sorts of questions about the “chain of evidence” and whether the samples are swapped and so on, and so forth. And you have to take these to the laboratory because the equipment required to analyze DNA is big, it’s bulky, you can’t carry it around. But I think five or ten years, we may be looking at a little hand held device. A sort of DNA sniffer, if you like, which you could take to the scene of crime, you could sniff over your sample, and within minutes up comes the genetic profile of the person. And, of course, if you’ve got a fully global database, you can then immediately tap into that and within another second identify your assailant or your perpetrator.

ALEC JEFFRIES: That’s a fine concept, but what does worry me more is that that sort of technology could equally well be used to interrogate DNA not for characters that specify your biological identity. In other words, that you are you or you are related to whoever. But you could equally well develop the same sort of device looking for genetic variations actually important in predisposing you to disease, like heart disease and so on. And that really does worry me because imagine a device which could be used really quite remotely from the medical community, whose job it is to council and to give proper advice on this sort of genetics. Technology is always a two edged sword in that there are going to be advantages and disadvantages. On the forensic side, I see real advantages.


JOHN HOCKENBERRY: Sometimes, you know, just hanging around a forensics laboratory can make you feel like you must be guilty of something....

MAITRE’D: So, perhaps monsieur would like to order a glass of water?

JOHN HOCKENBERRY: I don’t think so.

MAITRE’D: Seeing as monsieur is just standing around the Cafe not eating and not spending any money?

JOHN HOCKENBERRY: Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah.

MAITRE’D: Perhaps monsieur would care to leave a tip?

JOHN HOCKENBERRY: And perhaps monsieur would care to take a short break instead. I’m John Hockenberry. You’re listening to “DNA and the Genetics of Identity,” and we’ll be right back.

JOHN HOCKENBERRY: I’m John Hockenberry. This is DNA files. We’re here at the DNA cafe, where we’ve been listening in on the story of a gentlemen who’s having his DNA tested to see if he committed a crime. It’s a good story—we’ll get back to it in a minute-but I think it’s important to remember that DNA forensics don’t have to be about murder or unspeakable crimes. DNA can be used to establish family relationships-paternity cases, for example- and often it doesn’t involve people at all. The folks who breed plants and animals use DNA testing all time. I was talking about this with Sir Alec Jeffries during the break:

ALEC JEFFRIES: Oh yes, I mean the protection of genetic stock is terribly important and also establishing relationships. So, for example, a seed company would certainly wish to have some sort of genetic identification method and such methods do exist now which would enable them to say, right, that really is my stock and that another company who claims to have developed a parallel stock actually has stolen our stock and we can prove it genetically. That’s very important. And the same goes for animal breeding as well. I mean some of the very early case work we got involved in was paternity disputes, but not in humans. In fact these were dog paternity disputes, of all things. Which sounds crazy, but I mean if you have a champion bitch, for example, and you want to mate that with a champion sire to get champion puppies out of them, and what your bitch produces is some, you know, really awful-looking’ve got yourself a legal dispute, and you’ve got to establish parentage there one way or the other. And uh DNA can do that. It can also be used in forensic investigations connected with conservation biology. So, for example, one case I can bring to mind is a case of....I think he was a Belgian gentleman, who had a number of African green parrots who are on the endangered species list. And he claims he had adults-which he had legitimately- and he also had some young ones, and there was a strong suspicion that these youngsters were not bred by him but in fact had been caught in the wild, and he’d illegally imported them. So the genetic analysis was carried out, and lo and behold uh there was no way that the adults that he had could possibly have been the parents of these fledglings.

The only explanation was that these had been stolen from the wild, and in fact he was convicted.
And it wasn’t too long after that that a case that I wasn’t personally involved in, but I think really was quite a spectacular case, was the identification of the last of the Russian royal family. I saw Nicholas. His was Arena and three of their children. Now, the problem was they had no living relatives. So, what they then had to do was to use a rather unusual bit of human DNA called mitochondrial DNA. Now it turns out that the, czarinas, I’ll probably get this wrong, but it’s something like the czarina’s mother’s daughter’s, daughter’s, daughter’s, daughter’s, daughter’s son is His Royal Highness Prince Philip The Duke of Edinburgh.

MARY CLAIRE KING: Each of has exactly the mitochondrial DNA of our mother and of our brothers and sisters. And, our mother has exactly the same mitochondrial DNA as her brothers and sisters and her mother, and so on back to Eve.

JOHN HOCKENBERRY: This is Dr. Mary-Claire King, a geneticist at the University of Washington in Seattle. Some years ago Dr. King developed a technique for testing mitochondrial DNA, and she’s used it most famously to help a group in Argentina called “ The Grandmothers,” the “Abueyas de Plaza de Mayo”

MARY CLAIRE KING: The Abueyas de Plaza de Mayo are a human rights group who formed themselves in 1977 in Argentina as the consequence of the kidnapping and murder of their children, and kidnapping and disappearance of their grandchildren. That is the military dictatorship that took power in Argentina in 1975 began the systematic obliteration their opposition. And this included the kidnapping and subsequent murder of a recorded 9,600 individuals and probably close to 15,000 in total. And the kidnapping and sale- or retention in the military subculture, of so far recorded 221 children of their murder victims. That is, children were either born in captivity to young women who were murdered after they gave birth, or children who weren’t yet able to talk were kidnapped in the arms of their parents and kept in the military subculture or sold. As these children grew up the Abueyas de Plaza de Mayo, their grandmothers, the mothers of their murdered parents, set out to find out where they were. They needed a geneticist. I was that geneticist, and I’ve been working for them ever since. And they are very good at what they do. They have found, and we all have identified, 59 of these now young adults. And these kidnapped grandchildren are now, by in large, back with the families from whom they were stolen.

Of course, the stories are as individual as the children, and there are a few instances-very few- in which the children were adopted completely in good faith by people who had no idea that they were kidnapped, and in those instances the children have remained with their adopted families, but are aware of their biological families, are in contact with their biological families, and are very much aware that they were not abandoned, that there are people who love them who are their biological relatives as well as their biological relatives as well as their adoptive relatives.

But most were kidnapped and kept by people who, in some instances, were literally the people who murdered their parents. And in those cases, the grandmothers and lawyers working with them have attempted to bring these cases to court and we have served as the DNA identification lab on their behalf.

JOHN HOCKENBERRY: Dr. King’s laboratory is working to identify victims of human rights abuses all over the world—in Bosnia, Rwanda and Central America. It’s very important work. But still, when you think of the sheer amount of genetic data that’s being collected and stored these days, it worries some people. In this country a lot of states are building up databanks of DNA- mostly from convicted sex offenders, so far, while the FBI is working to combine state records into a national databank. The military keeps its own data banks. Medical researchers compile genetic data. It sounds like everyone has valid reasons. Law enforcement officials says it’s going to help catch violent criminals. The military needs DNA to identify bodies. And scientific research is a good thing, isn’t it? Everyone says the data will be kept nice and private under lock and key. But what if it gets unlocked? If you know my DNA, you not only know who I am, you can figure out who my relatives are, and whether I’m genetically predisposed to heart disease and a lot more. DNA is information. The more scientists learn about DNA, the more information there is and the more interesting it might become to let’s say, your insurance company, or your HMO, or your employer, or who knows.

LAWRENCE GOSTIN: I think the public really fails to recognize how much information is out there about them and how much information there will be about them.

JOHN HOCKENBERRY: Aha. This is Dr. Lawrence Gostin. He’s a law professor at Georgetown University in Washington DC. Gostin: We tend to think of privacy, that when we go to doctor, we tell the doctor something, or the doctor tests us and the doctor keeps it in her cabinet locked. But that’s not the way it works at all. And so, this kind of explosion of information, particularly genetic information about us, I think is rightly concerning to the public.

MAITRE’D: Excuse me, monsieur, I despise to interrupt but-

JOHN HOCKENBERRY: Wait a minute. Wait a minute, will you? This is important.

LAWRENCE GOSTIN: Many people believe that genetic privacy should be absolute. I think genetic privacy is very important, but I don’t think it can be absolute because it involves a complex tradeoff. On the one hand, you have an individual’s rightful claim to privacy and autonomy, but on the other hand, you have all of the collective good that we can do for society through genetic databases.

MAITRE’D: Monsieur, excuse, but I would like to ask, are you with that couple seated over there, the man and the woman?

JOHN HOCKENBERRY: Them? Oh them, no. No. I’ve just been sort of been standing near them.

MAITRE’D: Because they order only a little bit- nothing at all expensive-and then they sit and they talk and talk and they talk, and they don’t leave. They occupy the table interminably.

JOHN HOCKENBERRY: I can’t help you there, but I happen to know they’re having a very interesting conversation.

MAITRE’D: Is that so?

JOHN HOCKENBERRY: You bet . C’mere. Let’s you and me kind of ease over that way...and sort of...check it out...

MAITRE’D: ...with the utmost discretion....

LARRY MASSETT: Uh. Oh, man, I did it again. I’m so sorry.

ALICE: That’s fine. That’s....

LARRY MASSETT: That’s fine? OK.

ALICE: That’s fine.

LARRY MASSETT: All right. Well....

ALICE: Now, OK, so what happens next? Do you go back to the DNA lab?

LARRY MASSETT: Uh huh. Right. Well, let’s see, um, you remember we had added some chemicals to my DNA samples, uh the one sample from my blood test and the other one from the cigarette butt that was at the scene of the crime. And the chemicals were designed to break the DNA into the smaller fragments that we were interested in.

ALICE: Right. The ones where you would be different from almost anyone else.


ALICE: Right.



LARRY MASSETT: OK. So, well, then we do the same thing again. Uh you recall the business with electrophoresis?

ALICE: Where you put the DNA on a gel and run electricity through it?

LARRY MASSETT: Right. Right. Right. And the DNA molecules try to get away from the negative charge.

ALICE: Right.

LARRY MASSETT: Well, the thing is, how far they can run before the current is turned off depends on their size.


LARRY MASSETT: I mean, It makes sense, right? The,the little skinny ones go a long a way, and the big heavy ones don’t get so far.

ALICE: Just like real life, isn’t it?

LARRY MASSETT: Right. Except by now, since they’ve moved around to different places on the gel, the fragments are starting to look like bar codes.

ALICE: Bar codes? Like at the supermarket?

LARRY MASSETT: Bar codes. Right. OK. Now, at this point there’s too much left to do. We put another chemical onto the gel that will separate the DNA into single strands. As a rule the DNA has two strands that are in that double helix thing where they twist around.

ALICE: Why would you want to have it into single strands?

LARRY MASSETT: I’m getting there.


LARRY MASSETT: That’s the key to the whole thing. First we transfer the DNA off the gel onto what looks like a sheet of paper- actually I think it’s made of nylon. But that’s just to make a permanent record. The gel is no good anymore. We just throw it away-

ALICE: Yeah, like this meal that the restaurant is going to have to throw away.

LARRY MASSETT: Yeah. Right. OK. I’m getting to the good part. We have the DNA fragments on the sheet of nylon.

ALICE: -The DNA separated into single strands-

LARRY MASSETT: Right, and then finally, we add what the laboratory calls “the chemical probes.”

ALICE: . Ooh, I’m not sure I like the sound of that. What are these probes?

LARRY MASSETT: Well, believe it or not, the probes are also little fragments of DNA in single strands, but they’re synthetic DNA. People have got patents on them. You just buy them from a....a supply house, OK.


LARRY MASSETT: And when you add them to your sample DNA, they will latch on to only the very specific little parts of the chromosome that you are interested in. And, it’s like two sides of a zipper. You put them together, and bingo, the two single strands zip up and you have normal double-helix DNA again. But at last, you have only the bits you want to see. Everything else gets lost when you take the photograph. We can compare the unique DNA fragments from the cigarette with the unique fragments from the reference sample, my blood.

ALICE: The photograph, at last we got there. That’s very good.

LARRY MASSETT: Well, not so good...


MARK STOLLEROE: These films come out of the cassettes and they’re placed in the developer, and come out of the developer as fully developed film.

LARRY MASSETT: As it’s coming out now, it’s a transparent sheet...with a, by golly, little bar code things on it....

MARK STOLLEROE: Right. Exactly. And here is a sample that, as you can see, has a particular pattern on it, and this is in the lane that contained the DNA from the cigarette butt. Here is a sample of DNA which is from your reference sample.


MARK STOLLEROE: So, do those samples look like they match to you, or that they’re different? LARRY MASSETT: errr....ahhh....Well, I have to admit they look kind of like they match.

MARK STOLLEROE: These five individual films demonstrate that you have a matching pattern between the DNA recovered from this cigarette butt and your reference sample—your blood sample. The blood sample that we have shows that at each of these five chromosomal locations, the DNA pattern inherited from your parents matches the same DNA pattern that was recovered from the cigarette butt . And, the commonness of this particular pattern in the human population is approximately 1 in 1.5 billion of the Caucasian population, and about 1 in 6 billion of the African American population, and about 1 in 5 billion of the Hispanic population. So, this profile is certainly not a particularly common profile. And if you decide to present this evidence to a jury, then our laboratory will testify that there is indeed a match and that this particular DNA profile occurs less frequently than 1 in a billion of the world’s population.

LARRY MASSETT: Well, thanks a lot.....

ALICE: Oh that’s terrible. You must have felt awful.

LARRY MASSETT: Not great, I’ll tell you.

ALICE: Of course, a good legal defense team could still poke at the evidence. Maybe it did get contaminated somewhere along the line. Maybe, maybe it was planted. Maybe, hey, what about those numbers the lab was quoting, the 1 in 1.5 billion or whatever it was? Well, where do they get that from?

LARRY MASSETT: They get that from a science called population genetics. It seems that different populations- different groups of people- have somewhat different patterns of these unique DNA fragments. So, the odds change depending on whether I’m supposed to be from one group, one population, or another.

ALICE: So, it’s just statistics, isn’t it? It could be there’s something wrong with the math.

LARRY MASSETT: Well, that’s why I went to visit an expert: Dr. Kenneth Kidd. He’s a professor of genetics and psychiatry at Yale University. Very well known but, I’m afraid, very discouraging:

KENNETH KIDD: There are people who testify consistently for the defense who bring up a very large numbers of arguments against the way statistics are calculated standard manner for forensics, and will say, “well but it might be as common as 1 in 80,” even though you said it’s 1 in 20 million, “I can do these calculations it might be 1 in 80.” I reject that kind of numerology and I think most legitimate statisticians reject it. In most of the cases I know of where those arguments have been accepted by a court, it’s because the prosecution did not have a credible witness saying “That’s bullshit.” If there is a credible witness who understands this on the part of the prosecution, rarely does the defense succeed. There are other arguments, the arguments used in the OJ Simpson case, to get DNA essentially ignored

LARRY MASSETT: I’m thinking maybe there’s still some faint hope that I might belong to some unknown population....that might change my odds a little bit..

KENNETH KIDD: The question is if you are from an isolated village in Lithuania, what’s the chance that somebody else from that isolated village was at the scene of the crime? That’s a counter-acting factor as well. If it’s such a small population, and so rare, then there aren’t lots of people. There may be ONE other with a very similar pattern to yours, but it’s still on a global basis very rare. [music]

LARRY MASSETT: Oh man. I,I can’t...I’m, oh, I’m so sorry. I, well, maybe

ALICE: Just, just...

LARRY MASSETT: maybe you could take it to the dry-cleaners.

ALICE: Just, just leave it.

LARRY MASSETT: You know, well maybe you can just want a new dress anyway.

ALICE: You know.


ALICE: You know, it really does look like you’re guilty, doesn’t it?

LARRY MASSETT: Well, the evidence appears to tilt it that way. You know the only thing I don’t understand is the fingerprints.

ALICE: What about them? Never mind. Where’s my purse? Let’s go. That waiter is staring at us.

LARRY MASSETT: The fingerprints, you know, remember...remember my friend Barney who’s on the police force? Well, he said there were fingerprints at the scene of the crime, too, and he able to slip me of them. I had them tested, but for some reason they don’t match my prints. I,I,I don’t know why that is? It doesn’t.

ALICE: Oh, who knows. Tell it to your lawyer. Let’s go.

LARRY MASSETT: Go? You ready? You’re not...didn’t haven’t eaten the blue thing.

ALICE: Just, let’s go.

LARRY MASSETT: All right. We’ll go. Here. I’ll get your coat. I’ll get...

ALICE: I’ll get it myself. Don’t touch me, you unspeakable person....

LARRY MASSETT: It’s not like I’m contagious. I mean, it’s...and I’m sorry about the food. The food wasn’t that...

ALICE: I certainly hope not.

LARRY MASSETT: ...that great, but it’s probably not poisoned or anything.

ALICE: Let’s go.

LARRY MASSETT: It’s just...OK. We’ll go.

MAITRE’D: How terribly sad, monsieur. I hate it when they leave the Cafe DNA not happy.

JOHN HOCKENBERRY: Could we just say DNA. It’s sort of strange, though, isn’t it, what he said there at the end? Did you hear that about the fingerprints not matching?

MAITRE’D: If one were to judge by how clean is the napkin he left on the table, he may not have any fingerprints at all.

JOHN HOCKENBERRY: No. No. Seriously. Doesn’t that ring a bell somehow? He said his DNA matches DNA at the crime scene, but his fingerprints don’t. Doesn’t that mean something?

MAITRE’D: Oh! You are right! But of course! Indeed there is a case where one may have the DNA of another person but not the fingers! It can happen!


MAITRE’D: Certainly! You have never heard of the identical twin?

JOHN HOCKENBERRY: Identical twins, that’s right.

MAITRE’D: In this case, the evil twin. Wait! I must tell him! He must know!

JOHN HOCKENBERRY: Yeah. I guess he better call his mother.

MAITRE’D: I will even loan him the money for the call, why not? Here.


MAITRE’D: Take my jacket.


MAITRE’D: towel.

JOHN HOCKENBERRY: Get, get out of here. Oh.

MAITRE’D: You stay here. Fill in.


MAITRE’D: I must go. (exiting) Monsieur, Madame, wait! There is good news!

JOHN HOCKENBERRY: Oh. Well, that’s odd. Looks like I’m stuck here for a while. Anyway, this is the end of our program for today. I hope you had a good time, hope you learned a few things, hope I get out of here sometime soon....

Credits for The DNA Files:

The DNA Files is produced by SoundVision Productions, in Berkeley, California, and is made possible through the generous contributions of the National Science Foundation, the Department of Energy and the Alfred P. Sloan Foundation.

JOHN HOCKENBERRY: You’ve been listening to The DNA Files. I’m John Hockenberry.

For more information, and for an interactive look at some of the issues behind this program, go to our web site at For tapes and transcripts of this program and this series, contact VisABILITY at 303.823.8000. That’s 303.823.8000. To contact The DNA Files, send your email to The DNA Files’ Executive Producer is Bari Scott. The Project Director is Jude Thilman. Today's program, "Law and the Genetics of Identity", was produced by Larry Massett. The engineer was Robin Wise and its editor was Ann Finkbeiner. The role of Alice in the cafÈ was played by Kris Welch and the Maitre d’ was played by Elizabeth Stifter.

Managing Editors of The DNA Files are Loretta Williams and Catherine Stifter. Production manager is Catherine Gollery. Technical Director is Robin Wise. Adi Gevins is Director of Research and Creative Consultant. Sally Lehrman is Content Consultant. Original music composed and performed by Bill Frisell. Introductory Feature produced by John Rieger and edited by Gary Covino.

This has been a SoundVision production.

This program is distributed by NPR – National Public Radio.