When California forensic scientists were having a hell of time catching the "Grim Sleeper" serial murderer, they turned to a controversial "familial searching" technique—indirectly targeting a suspect's using DNA from their kin— and cracked the case.
But why the controversy, and how might it change forensic science and law enforcement? While effective, the indirect nature of the procedure has all but two states—California and Colorado—adopting a "wait and see" policy as they mull side effects and long-term "social ramifications," reports the New York Times:
The procedure involved widening the genetic net to include convicted felons whom they knew had not committed the murders but whose DNA profiles were partial matches to the suspect - similar enough to the suspect's that they might be related to him.
Lo and behold, Mr. Franklin's son had recently been convicted on a felony weapons charge, and his DNA offered a partial match to crime-scene DNA. And for the first time in California, that kind of one-degree-of-separation search ultimately led to an arrest.
One issue, raised by the ACLU in SoCal, is that the long lists of convicted felons created by partial matches could lead to authorities intruding on, or arresting, family members who haven't committed a crime.
For now, the technique remains in the employ of California investigators, who must report to a special committee of legal experts at each stage of the DNA matching process. If the facts add up, the name is released to the police, who are free to arrest the suspect (as they did with the Grim Reaper).
So the technique worked, in this case—would you be OK with a few privacy violations and some hurt feelings and misunderstandings to catch a few more? [New York Times]