Investigators are reviewing at least 30 unsolved murder cases for possible links to an unidentified serial killer suspected in at least 11 slayings since 1985.
The unsolved cases have many similarities to those carried out by the serial killer, including locations where the bodies were dumped, Los Angeles police Detective Dennis Kilcoyne said Friday.
He estimated at least six of the 30 cases would be linked to the murderer.
"We don't know who he is, but his numbers are building," Kilcoyne said. "Once we are done, I am quite confident this will exceed anything we have ever seen in the city."
Kilcoyne's comments came after the Los Angeles Police Department held a news conference to announce for the second time a city-funded reward of up to $500,000 for information. The reward was first announced last week but authorities distributed the wrong phone number for the public to call so responses were limited.
The killer apparently operated in two distinct periods, first from 1985 to 1987, when he allegedly killed seven women and a man. He is known to have killed again three times since 2002, most recently in January 2007.
The victims in the 30 unsolved cases were all women. Many were dumped in a South Los Angeles location, the same area as many of the killer's other victims, Kilcoyne said. Many of the killer's victims worked as prostitutes and he had sexually abused them.
"He's a maniac. He's a broken person," Deputy Police Chief Charlie Beck said when asked about possible motives.
Police have a DNA sample of the killer but have been unable to find a match in any prison database. Detectives want to run the sample against wider databases to see if it is similar to any family members, but California Attorney General Jerry Brown has not yet approved this.
One physical description exists, taken from a victim who survived a 1988 attack. She said the assailant was a black man in his 30s driving an orange Ford Pinto, though police said her account is not reliable because she was so traumatized.
Kilcoyne said the killer now would likely be aged from 43 to his late 50s.
The hiatus between episodes prompted the LA Weekly newspaper, which first reported the case, to dub the killer the "Grim Sleeper."