Frustrated by their inability to find the notorious killer known as the Grim Sleeper, whose DNA was not in a law enforcement database, Los Angeles police this spring asked the state to look for a DNA profile similar enough to be a possible relative of the killer.
In April, state computers produced a list of 200 genetic profiles of people in the database who might be related to the alleged serial killer. Among the top five ranked as the most likely relatives was a profile that shared a common genetic marker with the crime-scene DNA at each of 15 locations that the crime lab examined.
Scientists knew that a profile with that sort of matching pattern indicated a parent-child relationship. To winnow the candidates further, and knowing that their suspect had to be a man, they tested the DNA of the 200 offenders whose profiles resembled the crime-scene DNA to determine if any appeared to share the Y chromosome, which boys inherit from their fathers.
There was one match, and it was the same profile that had shared all 15 markers on the first round of testing.
Excitement swept the room at the state DNA laboratory in Richmond where the match was made. Jill Spriggs, chief of the state's Bureau of Forensic Services, recalls a feeling of "amazement" when she learned of the breakthrough: The two rounds of tests almost certainly had located a son of the suspect — the first high-profile U.S. case cracked by a technique known as familial DNA searching.
Even then, though, state scientists moved gingerly, anxiously trying to ensure that nothing would go wrong.
They did more tests, then called a meeting of the scientists and lawyers who oversee such searches.
"We were all very businesslike," said Spriggs, recalling the meeting. "We made very sure we were following all the procedures, kind of like a checklist approach. "
Although each step was made with caution, Spriggs said the group knew it was a part of something "revolutionary."
"We were very excited," she said.
Familial searching has been done for years in Europe, Australia and New Zealand, but technical, legal and ethical concerns have kept the FBI from pursuing it in the United States, where California and Colorado are the only two states that have embraced it fully. Pressed by prosecutors, California Atty. Gen. Jerry Brown approved familial searching two years ago, and Colorado began using special software to track relatives of suspects at about the same time.
State lawyers had warned Brown that a bungled familial search could lead defense lawyers to challenge the state's entire DNA testing program.
Instead, the ability of the technique to identify a suspect in the Grim Sleeper case, Lonnie David Franklin Jr., who was charged Thursday with 10 counts of murder, has emboldened and thrilled advocates of further DNA testing. They hope to see familial DNA searching quickly spread to additional states.
"This case is the poster child we have been waiting for," declared Harvard geneticist Frederick Bieber, a medical school professor. "We have been waiting for a case like this to hit a home run."
Studies show that prison inmates tend to have family members who also have been behind bars. When the source of DNA from a crime scene cannot be identified, there are "even odds" that the unknown suspect will have a relative with DNA in the database, Bieber said.
Unrelated people can share the same genetic markers, but siblings and parents and their offspring usually share a greater number. Once a relative is identified, authorities can use that person as a lead to trace a suspect. The success rate is estimated at 10% to 14%.
Skeptics have argued that familial searches invade the privacy of people who happen to have a relative in the database and may violate constitutional guarantees against unwarranted searches. So far, however, no one has challenged the use of familial searching in California, and an attorney for the American Civil Liberties Union said Friday that the state's handling of the Grim Sleeper case made the group "more comfortable" with the process.
"From our perspective, if you are going to use familial DNA searching, this is the kind of case you should use it for, and the kind of precautions they took in this case are the kind that should be taken," said Peter Bibring, staff attorney for the ACLU of Southern California.
He said state law should require the procedures used in the Grim Sleeper case to be followed in all familial searches.
At each step of the way in the forensic investigation, the familial search committee met and voted. After verifying the DNA results, the group voted unanimously to give to the intelligence division of the Department of Justice the name of the offender who had been identified as the likely relative of the suspect.