Over nearly two decades, a serial killer has shot and strangled at least 11 people, often dumping their battered bodies in alleyways in Inglewood and Los Angeles.
Most were black women, the youngest just 14. The latest was found last year, shrouded in a garbage bag.
Police have determined through DNA and other evidence that the killings were the work of a single person. But the DNA does not match any of the millions of genetic profiles of convicted criminals in law enforcement databases, and detectives have few other clues.
Now Los Angeles Police Department investigators want to search California's DNA database again -- not for exact matches, but for any profiles similar enough to belong to a parent or sibling.
The hope is that one of those family members might lead detectives to the killer.
This strategy, pioneered in Great Britain, is poised to become an important crime-fighting tool in the United States. The Los Angeles case will mark the first major use of California's newly approved familial searching policy, the most far-reaching in the nation.
But the specter of scrutinizing families based exclusively on their possible genetic relationship to an unknown suspect makes privacy advocates and legal experts nervous. They argue that it effectively expands criminal databases to include every offender's relatives, a potentially unconstitutional intrusion.
'Sins of your father'
"There is kind of a queasiness about having the sins of your father come back to haunt you," said Stanford University Law Professor Hank Greely, who supports familial searching despite those concerns. "It feels like we're holding people responsible for the crimes of their family."
Because the technology isn't perfect, families with no connection to the perpetrator inevitably will be investigated, some scientists and legal experts say.
In the United States, officials are trying to balance the technology's promise and perils, pledging to use databases to identify relatives only for serious crimes and when all other leads have been exhausted.
It took a dogged three-year campaign by a Colorado prosecutor to bring down the barriers to familial searching in the United States.
Denver District Attorney Mitchell Morrissey began his effort in 2005, when investigators came across DNA profiles in law enforcement databases that resembled, but did not match, genetic evidence left behind by three Denver rapists.
Such partial matches were typically ignored by crime labs. But the similarities tantalized Morrissey. In each case, the profile shared at least half the genetic markers with that of the rapist, suggesting a possible biological relationship.
Morrissey was determined to follow up on the partial matches to the Denver rapists, but he quickly ran into roadblocks.
The DNA profiles Denver had found belonged to felons in Oregon, Arizona and California. But the FBI, which controls the national DNA database system, prohibited states from sharing information about people who were not suspected of a crime.
Thomas Callaghan, then gatekeeper of the national DNA database, told Morrissey that disclosing information about partial matches might by viewed by the courts as "database creep," a use of the database beyond its original purpose, the prosecutor recalled.
6 million profiles
A lot was at stake for the FBI. The bureau had built the national database from 460,000 DNA profiles in 2000 to 2.8 million in 2005. In a few short years, the federal government would add people who had been arrested -- but not convicted -- of crimes. The database system now holds more than 6 million profiles.
The FBI feared that racing ahead to familial searching could prompt a backlash and endanger database expansion, Morrissey said.
Frustrated, Morrissey decided to go over Callaghan's head. "Your policy protects murderers and rapists," Morrissey wrote in June 2006 to Joseph DiZinno, then Callaghan's boss.
A couple of days later, Morrissey went through the pink slips of telephone messages. One was from Robert Mueller, director of the FBI. He wanted to help.
At Mueller's order, the FBI lab reversed its earlier position, adopting an interim policy that permitted states to pursue partial matches that turned up during routine database searches.
Oregon and Arizona authorities agreed to cooperate with Morrissey, but additional genetic testing determined that neither of the profiles belonged to relatives of the rapists.
Undaunted, Morrissey pressed his case in California. California Attorney General Bill Lockyer and his successor, Jerry Brown, initially refused to help, even with the FBI's new policy.
After being referred to Michael Chamberlain, one of the attorney general's legal advisers, Morrissey was blunt: "I explained to him clearly that was not something we were going to give up on. If the assailant "raped another woman or hurt a child, I was coming straight back to California, and I wasn't going to be patient."
UPDATED: Please read and follow our commenting policy: