The familial DNA program was enacted by Brown in April 2008 as a way to fight violent crimes when there is "serious risk to public safety," according to the attorney general's office. California is the first state to use familial searches.
The high-profile case had languished unsolved, and had haunted the files of the LAPD cold-case unit for years.
According to the attorney general's office, the suspect's son was arrested and convicted in a felony weapons charge and swabbed for DNA last year. When his DNA was entered into the database of convicted felons, detectives were alerted to a partial match to evidence found at the "Grim Sleeper" crime scenes.
Police began investigating Franklin's son's relatives, and found a match in Lonnie Franklin. Police said he had never been a suspect until now.
The data bank, which contains more than 1.5 million samples, is the third largest criminal database in the world. Only data from convicted felons is collected, according to Brown, and a number of safeguards are taken before the Department of Justice releases the information to police.
Los Angeles Police Detective Dennis Kilcoyne, who headed the investigation, said it was the second time a query was run for familial connections in the "Grim Sleeper" case. From the DNA matches, a tight circle of law enforcement officers zeroed in on Franklin based on the suspect's residence, location of the victims, his race and age.
Familial DNA database searches have come under fire from privacy and civil liberty advocates, who argue, among other things, that they put more minorities, who are disproportionally represented in the database, in an at-risk group.
The Supreme Court has upheld the constitutionality of familial DNA sample collection and searches. Brown said the office of the attorney general will be in court again next week defending the technique, and raised the possibility of more legal challenges.
The killings of 10 young black women and one man, beginning in 1985, have all been blamed on the "Grim Sleeper." Franklin has not been charged for the shooting death of 36-year-old Thomas Steele, but police said they believe his death is connected to the other killings.
The cluster of killings stopped in 1988, but 14 years later police said they linked new murders to the same man, nicknamed the "Grim Sleeper" for the long lull between slayings. The most recent murder happened in January 2007.
Los Angeles Mayor Antonio Villaraigosa praised law enforcement officials for their "exhaustive detective work" in the past 25 years that led to nabbing the suspect. More than two dozen investigators worked to find the "Grim Sleeper."
"I'm proud to announce that this terror has finally come to an end," Villaraigosa said at today's news conference.
Relatives of the victims who were in attendance said they were elated and thankful that the police finally brought the alleged killer to justice.
Police closed off the block on 81st Street in South Los Angeles where Franklin lived Wednesday and the arrest was made. Residents were shocked.
Neighbor Donna Harris, who's known Franklin for nearly 20 years ago, said the retired mechanic was supposed to fix her car this morning.
"Everybody on the block, we all knew if anything was happening with anybody's cars, he was always there for us. Especially the ladies," Harris said. "Even if we weren't at home, instead of calling Triple AAA, he would help."