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New Rule Allows Use Of Partial DNA Matches

Publication Date: 
January 25, 2010
The New York Times
Jeremy W. Peters

Professor Hank Greely weighed in on a new rule that allows partial DNA matches to pursue suspects using a family's shared genetic traits:

New York has become the latest of a handful of jurisdictions to permit a controversial use of DNA evidence that gives law enforcement authorities a sophisticated means to track down criminals.

Under a state rule approved in December, DNA found at a crime scene that does not exactly match that of someone in the state’s DNA database can still be used to pursue suspects if the DNA closely resembles that of someone on file.

Since family members share genetic traits, a partial DNA match allows investigators to narrow searches to relatives of people whose DNA is already in the state database, forensic experts say.


“I’m not sure how meaningful it is to say, ‘You can’t do this search just for the partial match,’ ” said Hank Greely, a professor at Stanford Law School who has studied the use of partial DNA evidence. “You can always say you’re looking for a perfect match.”

Still, Mr. Greely said he believes that partial matching, while not perfect, is less harmful than its opponents say.

“Let’s say you find a convict who’s a partial match. And you find a brother who lives in the area where a crime was committed,” he said. “Now the brother has been put through the unpleasant experience about being involved in a possible crime, but the test will say conclusively whether or not he did it.”

Of course, Mr. Greely added, that does not “underestimate the unpleasantness of being a suspect — even if it is only briefly.”