In an effort to fully exploit DNA databases, investigators in California are planning to look for partial matches from crime scenes. If a forensic sample partially matches a sample on file, it likely means that it was left by a relative of the person on file. Although the "match" isn't for a suspect, they'll be investigated to try to find the suspect in their family tree.
Critics are concerned about the privacy implications of this.
California takes lead on DNA crime-fighting technique - Los Angeles Times
Civil libertarians oppose using DNA databases to search for relatives of unknown offenders, saying it puts family members under "genetic surveillance" for crimes they did not commit. For now, all the people in the state's database are convicted offenders, but the state plans to expand the database next year to include arrestees, heightening concerns over privacy.
Critics say familial searching could expose sensitive and secret genetic relationships. A son, for example, could learn that his father was not his biological parent. DNA databases also reflect the racial and ethnic biases of the justice system, exposing minority communities to more surveillance than others, critics maintain.
FBI officials in charge of the national database network have also expressed concerns, making them unlikely allies of civil libertarians on familial searching. They urge a cautious approach, worrying that the courts will balk at this type of sleuthing. No law specifically authorizes it, and some legal scholars consider it unconstitutional because they say it amounts to an unreasonable search.
Brown called such objections hypothetical. The policy forbids the release of the names of relatives until genetic tests and analysis convince the state that the person is indeed a relative.
"It is still not going to be a fail-safe system, and we are going to make mistakes," said Simoncelli, the ACLU science advisor. "We are opening the door to using the database in such a fundamentally different way than the purpose for which it was established."