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For years, genealogists have used DNA technology to identify unknown relatives, and law-enforcement officers have used the technology to identify criminals. Now, those two threads have merged. Investigators are now regularly using partial DNA matches to track down criminal suspects through their family members who are already in a DNA databank.
NPR's Ari Shapiro has the latest installment in his series on the ethics of emerging DNA technologies.
ARI SHAPIRO: In the 1990s, daytime TV talk show hosts like Maury Povich realized that DNA paternity tests were a great new way to boost ratings.
(Soundbite of TV show "Maury")
Mr. MAURY POVICH (Host, "Maury"): When it comes to one-month-old Bryce(ph), Michael, you are not the one.
(Soundbite of cheering)
SHAPIRO: Who's-your-daddy-type shows become a staple of daytime TV. And where Ricki Lake and Montel Williams led the way, criminal investigators soon followed.
Ms. NOLA FOULSTON (Wichita District Attorney): It sounds like hocus-pocus, but it's a program of scientific work that is very well supported and has been over the years.
SHAPIRO: Wichita District Attorney Nola Foulston spent almost 20 years chasing the killer who called himself BTK - for bind, torture, kill. When she started in the '70s, nobody was using DNA evidence. But by 2005, when Foulston felt she was closing in on her man, familial DNA connections were a key part of the investigator's toolkit.
Foulston had samples of the killer's DNA from crime scenes, and she had a strong suspicion that BTK was a man named Dennis Rader. She needed to know whether Rader's DNA matched the killer's. But police couldn't just walk up to Rader and ask him for a sample.
Ms. FOULSTON: They didn't have everything they needed at that point to take him into custody. So you'd be leaving a guy out there with his DNA sample hanging out. And he was not inactive; he continued to plan homicides up until the day that we caught him.
SHAPIRO: The team learned that Rader's daughter had recently been in the hospital for a pap smear. So under a judge's order, the hospital gave investigators a sample of the daughter's DNA. In 24 hours, the results came back. It was a familial match, just like daytime television. District attorney Foulston says that's all the police needed to pick up Dennis Rader.
Ms. FOULSTON: When Mr. Rader was brought into the special location that we had, he was very cordial with the officers after they had picked him up and he appeared to like, very much, Lieutenant Landwehr.
Kenny said to him, you know, you know why you're here. And he said, well, I assume it's about BTK. And he said, well, yeah. And he said, would you be surprised to know that the father of your daughter is BTK? And there was just a stunning silence. And they looked at him and the FBI agent said, tell us who you are. And he looked at them and he said, I'm BTK. You got me.
SHAPIRO: The Wichita investigators were lucky. They had a specific target and they just needed a family member to validate their hunch. That's not how it usually works. Typically, investigators will take DNA from a crime scene and compare it to all of the samples in the databank. They might find that the criminal is not an exact match with anybody on file, but the sample is so close to one in the databank that the criminal must be related somehow to the person on file.
Mr. CHRIS ASPLEN (Former Director, National Commission on the Future of DNA Evidence): And the question that becomes is, is that a legitimate investigative lead?
SHAPIRO: Chris Asplen used to direct the National Commission on the Future of DNA Evidence, and he's now a private consultant on DNA technology.
Mr. ASPLEN: And I would suggest, absolutely, it's a legitimate investigative lead. As much as, you know, we know the guy's last name is so and so and such and such, would you ignore that because you didn't have the person, but rather you had the person's brother? Certainly not.
SHAPIRO: But civil libertarians don't think it is the same as a last name because your name is public information. Your DNA profile is not. And as the ACLU's Tania Simoncelli points out, you're only going to be pegged in a familial match if your DNA profile happens to be on the databank already.
Ms. TANIA SIMONCELLI (Science Advisor, American Civil Liberties Union): Where I have problems is the creation of these large databanks that are, you know, expanding now to innocent people, and law enforcement employing these other techniques that really undermine the inherent notion that one should have privacy in their DNA.
SHAPIRO: DNA databanks started with convicted felons. But in some states, they now include people who've committed misdemeanors or even just people who've been arrested. And since more minorities are in the databank, more minorities will be investigated as familial matches.
DNA expert and Harvard Professor David Lazer does not think that's reason enough for investigators to abandon familial searches.
Professor DAVID LAZER (DNA Expert, Harvard University): If we prohibited investigative processes that led to the investigation of innocent people, we would just stop investigations altogether, right, because investigations always yield talking to and suspecting people who turn out not to be guilty.
SHAPIRO: Finding a familial near match in the databank is actually harder than finding an exact match. One expert said familial matches are like finding a needle in a haystack. That makes familial searches much more common at the state level than at the national level because compared to individual states, the national DNA database is a much bigger haystack.
Ari Shapiro, NPR News.