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The British got their first familial-DNA conviction in 2004 when a truck driver died after a brick was thrown through his windshield on a motorway in southern England. DNA found on the brick produced no direct hits in the U.K.'s database but gave police a near match to a man whose brother Craig Harman, after providing authorities with a DNA sample, turned out to be a perfect match. Harman later confessed to the crime. The British have conducted some 210 familial DNA searches in the past nine years, with a conviction rate of 11.9%.
Familial DNA searches are not foolproof. Complete strangers can share significant similarities in their genetic makeup, so searches generate many false positives, which must be painstakingly eliminated by further refining the computer search or by consulting investigators. Still, even familial DNA's critics agree that it will lead to the identification and conviction of more criminals, in part simply because of the data pool available. U.S. Department of Justice statistics show that 48% of people in jail have a relative who has also been incarcerated.
But the U.S. has been slow to adopt familial searches largely because of privacy concerns. Stephen Mercer, chief attorney in the forensics division of Maryland's office of the public defender, says familial DNA searching will subject families of a convicted felon to "permanent genetic surveillance" and warns that the practice would disproportionately invade the privacy of African Americans, who make up 13% of the U.S. population but 38% of the prison population. "If success is the only criterion for adopting a new technique," Mercer tells Time, "then goodbye to the Fourth Amendment, goodbye to privacy in the U.S."
Denver district attorney Mitch Morrissey, a strong proponent of familial DNA searches, points out that crime labs performing DNA searches should not disclose any names to the police until they have found a probable match. "This is not guilt by association, not even probable cause," he says. "It is a lead, which may or may not lead to an arrest." Morrissey concedes that African Americans are overrepresented in law-enforcement DNA databases but says "that doesn't mean you shouldn't use a scientific tool that is effective to find a guilty person."
How familial DNA searches square with privacy is a question that will eventually find its way into U.S. courts. Under pressure from policy chiefs to clarify its position, the FBI decided in July 2006 that it would not perform familial DNA searches of its own national CODIS database but would permit individual states to use familial searches within their own jurisdictions.
In the midst of this charged debate, Spriggs went to California attorney general Jerry Brown--now the governor--to persuade him to allow familial searches. Brown was initially opposed. Was it right to use someone innocent of a crime to get at someone who was guilty, his team asked, just because they were blood relatives? And what if a familial search turned up unacknowledged offspring or unexpected paternity?