Using a relative's DNA to catch criminals
When a woman was brutally raped in Denver in 2003, DNA found at the crime scene was similar to that of a felon whose genetic profile was kept in Oregon's DNA database--so similar that the man in Oregon was probably a close relative of the suspect, says Denver District Attorney Mitch Morrissey. But FBI rules on interstate cases prevented Oregon's crime lab from sharing the man's name with out-of-state police, effectively stalling the investigation.
"This may be the father or son of the rapist I'm looking for," says Morrissey. "At least give us the chance to look."
He may soon get his chance. Prompted by cases like Morrissey's, the FBI is making it easier for police to use DNA databases to investigate the relatives of the 3.3 million known criminals whose genetic profiles are being kept by the government. In limited situations, crime labs may now release the name of a person in the database who is not actually a suspect but whose DNA is similar to DNA recovered from a crime scene--leading police to then investigate that person's family. And some prosecutors are pushing states,which set their own policies for in-state cases, to even more aggressively use so-called family searching--a potentially powerful crime-fighting tool whose effect on civil liberties alarms privacy advocates.
Attorneys in Maryland are planning what appears to be the first of an expected slew of legal challenges to familial searches, saying they invade the privacy rights of families.
"People who have never had any contact with the criminal justice system are now exposed to indefinite genetic surveillance by the government," says Stephen Mercer of Sandler & Mercer in Rockville, Md.
The FBI's interim plan comes amid a rapid expansion of DNA databases, which were first created in the late 1980s to track sex offenders. In 1990, Virginia became the first state to take DNA samples from all felons. Today, nearly every state does so. At least 38 states collect DNA from those convicted of some misdemeanors, and, by January, at least seven states and the federal government will track people arrested for certain serious crimes.
Searching for the families of criminals, common in Great Britain, has rarely been used in the UnitedStates. It works like this: Crime scene DNA can be gathered from anything from a drop of blood to saliva on a cigarette butt. Labs compare areas of the DNA molecule called alleles, with 26 identical alleles needed for a match. A match to fewer alleles could mean a suspect is a close relative of a known criminal. Harvard geneticist Frederick Bieber compares it to getting a partial license plate number on a getaway car. "If you had all the numbers but one, would you ignore it?"
But even unrelated people can share some of the same alleles, and just how close a match is needed to guarantee that a suspect is a relative is still disputed. The new FBI plan allows state labs, if they choose, to report a match of at least 13 alleles, with bureau approval in each case. The bureau's scientific advisory board will review the plan, which went into effect last month, before any final policy is set. Lab director Joseph DiZinno says the FBI does not condone a technique used in Britain in which police search the database for a list of people most genetically similar to crime scene DNA and then pursue their relatives. But, geneticist Bieber says, the FBI's policy is "a step in that direction." And some are pushing to do so.
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