Posted on July 16, 2010

A Successful Use of ‘Familial’ Matching

Maura Dolan, Los Angeles Times, July 15, 2010

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.


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 Attorney General 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 July 8 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.


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.


After an examination of birth records and geographical data showed the offender’s father was the right age and lived in the right place to have committed the killings, the committee met again to decide whether to give the information to the LAPD. Again, the vote was a unanimous yes. Spriggs said no one raised objections.

She flew to Los Angeles with Craig Buehler, chief of the Bureau of Investigations and Intelligence, and met LAPD officials in a conference room at Cal State Los Angeles.


The familial search cost the state $40,000, with much of the work done on overtime, Spriggs said. She said she and other scientists never doubted they could nab a criminal suspect this way, and that statistically they were due for a breakthrough.



The biggest immediate concern is that familial searches are racially discriminatory. {snip}


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