LOS ANGELES (AP) — Los Angeles Police Chief Charlie Beck says investigators will examine more than 30 cold case files for possible links to a suspect in the “Grim Sleeper” serial killings.

Beck said Friday that the cases, dating back to 1984, will be reviewd with new information gleaned from the investigation into Lonnie Franklin Jr., who was arrested Wednesday and accused of murdering 10 people.

The name “Grim Sleeper” came about because of a 14-year gap in slayings linked to the same killer. The most recent case was in 2007, and Beck says it appears he has not been active since then.

Police say DNA evidence ties the 57-year-old Franklin to the killings. His full DNA profile will be uploaded into a federal database to check for matches.

Franklin was arrested Wednesday at his lime-green house, which is just three doors down from a home that was searched extensively by police 22 years ago after the killer’s only known survivor led cops there.

Police Chief Charlie Beck also noted that billboards plastered with a $500,000 reward and the suspect’s police sketch were posted just eight blocks from Franklin’s house and he drove by them every day.

“We think that impacted the suspect’s behavior in one of two ways: either he became more careful or he stopped his behavior for a number of years. That’s an evolving theory,” Beck said. “It’s going to be difficult to be absolutely certain absent his confession.”

Law enforcement said despite more than two decades of old-fashioned police work, they were eventually able to crack the case using a brand new — and controversial — technique of “familial DNA.”

In early June, the LAPD submitted DNA evidence found on victims to the state Department of Justice, where geneticists in ran it through a database of 1.5 million samples.

The database found no identical matches, but did find a “familial” match to a convicted felon whose DNA indicated he was either a brother or the son of the killer. An earlier search in 2008 had found no familial matches, but Franklin’s son was added to the database in recent months for a felony weapons conviction.

State investigators alerted the LAPD of Franklin’s identity on June 30 after verifying the match through birth certificates, incarceration records and comparing Franklin’s address to locations where the victims were found.

But police still needed a sample of Franklin’s DNA to definitively match it to the genetic material found on the victims.

An undercover officer pretending to be a waiter in Los Angeles collected tableware, napkins, glasses and pizza crust at a restaurant where the suspect ate, allowing detectives to obtain a DNA match.

Franklin made a first court appearance Thursday on the murder counts as well as one count of attempted murder and special-circumstance allegations of multiple murder that could lead to the death penalty or life in prison without possibility of parole.

His arraignment was postponed until Aug. 9 at the request of his defense attorney, Regina Laughney, who declined to comment on the case.

California Attorney General Jerry Brown said it marked the first time in the nation that familial DNA had been used to break a case of such magnitude. He expects legal challenges but believes the case will hold up to the scrutiny, in part because officials only searched DNA from convicted felons and were careful to limit the search to a smaller universe of samples that bore certain pre-determined genetic markers.

Advocates of familial searches believe they will solve many more crimes in which there is DNA evidence. Others worry that it creates the potential for guilt by association: A person could come under suspicion simply if a family member’s DNA is in a criminal database.

“There will be legal challenges,” he said. “But I think this is an excellent case we’ve done under controlled conditions and the procedures have been run very carefully by our lawyers.”

The first conviction using familial DNA is believed to have happened in Denver, when a man pleaded guilty in September to breaking into a car. He was nabbed during a research project conducted by Denver District Attorney Mitch Morrissey’s office to test the effectiveness of software developed by his office to winnow down what could be long lists of suspects with similar DNA.

Using familial DNA, Morrissey said investigators have been able to trace DNA to its source in 12 cases, but only one resulted in charges. Other issues with the cases, including victims unwilling to participate in prosecution, meant charges were not filed in those instances.

Investigators have identified about a dozen unsolved cases to further review, said Detective Dennis Kilcoyne, the lead investigator.

Although he also anticipates a long legal battle, Kilcoyne was certain of the case against Franklin.

“We have done our job correctly on all this cutting edge science to make the charges stick,” he said.

The detective said Franklin has not been charged in the death of an 11th suspected victim, a man, because there was no DNA evidence.

LaVerne Peters, the mother of the last known victim, expressed her gratitude for police as she clutched a framed photo of her daughter, Janecia Peters outside the police headquarters. Her daughter was killed in 2007 at age 25, leaving behind a 5-year-old son.

“There’s no greater pain than the loss of a child,” said Peters, now guardian of the 8-year-old boy. “You wanna just fall to your knees and stay there. Some people ask, ‘How do you go on?’ and I say, ‘I get up and I put one foot in front of the other and keep going.’”

Copyright 2010 The Associated Press.