ROBERT SIEGEL, Host:
Late last week, the Los Angeles police made an arrest in the case of The Grim Sleeper, a killer who had eluded them for 25 years and at least 10 murders.
ANTONIO VILLARAIGOSA: Thanks to the recent use of DNA evidence and, even more importantly, two decades of exhaustive detective work, we have our suspect.
SIEGEL: And welcome to the program, David Lazer.
DAVID LAZER: Hello. Thank you for having me.
SIEGEL: And first, how rare is familial DNA testing?
LAZER: Well, it has not been widely used in the United States. Primarily it has been used to some extent in Colorado and in California. And this is the, really, the biggest success story. There was a notable case in North Carolina, where actually they got not only a familial match, but then they - that also resulted in the exoneration of someone who had been in jail for some time, Darryl Hunt.
SIEGEL: Ten unsolved murders in the L.A. case, with a pile of DNA evidence from multiple crime scenes - this sounds like the ideal application for this kind of technique, when you have no doubt as to the DNA of the person you're looking for. Can you imagine it being used, though, in a variety of other situations?
LAZER: The facts in this case where you have matching evidence from multiple crime scenes then matching a suspect, looks like a pretty compelling case. However, there are going to be more difficult cases where, let's say, you have a cigarette butt at a crime scene. May or may not be from the perpetrator of the crime but, you know, that's a more general problem with any investigation is that sometimes some of the facts, some of the clues mislead you to the wrong person.
SIEGEL: What do you think of the argument that criminal databases reflect the population of people who've been charged with crimes; they are disproportionately black and Hispanic; a disproportionate number of blacks and Hispanics with ne'r-do-well cousins or absentee fathers, who've committed crimes, could find themselves under police surveillance if this technique were used widely?
LAZER: Well, it's definitely troubling that indirectly brings in, you know, potentially tens of millions of people into the database, and they're going to reflect the demographics of the people who have their samples in the database. And that system is already tilting heavily in the direction of African-Americans, Hispanics. That is certainly, I think, something that is troubling about the use of familial searching.
SIEGEL: By the way, when we speak of all the databases that law enforcement might check to see if somebody is in there, I think the military database is still off limits to criminal investigators, but how many people are we talking about? How many Americans have genetic profiles that might be accessed and might be part of a search?
LAZER: The size of the offender database in the United States is a bit over eight million people. And that currently is the only database that is systematically searched.
SIEGEL: You know, on TV shows, someone says let's check the DNA and five minutes later someone from the crime lab walks in with the answer. What are we talking about nowadays in terms of delays to actually get an answer to a question about a DNA match?
(SOUNDBITE OF LAUGHTER)
LAZER: Obviously, if you have a serial murder case, that goes to the front of the line. And in this particular case, they did the analysis very quickly. Not as quickly as you see on "CSI," but very quickly.
SIEGEL: Professor Lazer, thanks a lot for talking with us.
LAZER: Okay. Thank you so much, Robert.
SIEGEL: That's David Lazer of Northeaster University. He's the editor of the book "DNA and the Criminal Justice System."
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