Dutch Cold Case Murder Solved After 8000 People Gave Their DNA

sciencewatcher writes "A 1999 cold case rape and murder in The Netherlands has been solved. Dutch police asked 8000+ men living within 5 kilometers of the crime scene to volunteer their DNA so that the murderer could be traced through (close or distant) family members sharing part of this DNA. As it turned out, the man now in custody turned in his own DNA, resulting in a 100% match. The request of the police was discussed here on Slashdot in September. The percentage of people participating was closing in on 90%; in the midsize town of the victim it was 96%."

Comments

Sounds improbable

[dinfinity]

"As it turned out, the man now in custody turned in his own DNA, resulting in a 100% match."

If he was really the guy who did it: Was he wondering whether the DNA-research would work? Why not just turn himself in?

Re:Sounds improbable

[RabbitWho]

If 96% of people had done it the social pressure might have been insurmountable. He might have figured if he was the only person in the village who didn't give DNA the police would investigate him and find him anyway, so he might as well give the DNA, hope that there would be a mistake, or hope that he could claim "If it was me, then why did I give them my DNA?"

Re:Interesting

[readin]

I find this method seriously scary due to the probability of a false positive. I mean, suppose you have a system that only fails once in a million times and the killer has already left the country. You ask the two million people in the metropolitan area to submit DNA. You get on average two matches. One doesn't have an alibi. You take him to trial and tell the jury that he not only doesn't have an alibi, he had a 1 in a million DNA match. It sounds pretty convincing. It is very possible the jury won't have the understanding of statistics to ask "was this a sweep or did you only test a couple of likely suspects?" Nor is it likely that the information will be volunteered by the court.