SACRAMENTO, Calif.—California investigators tracked down the former policeman who they suspect is the Golden State Killer responsible for dozens of rapes and murders by comparing crime scene DNA to genetic information on genealogy websites, a prosecutor said on Thursday.
The suspect, former police officer Joseph James DeAngelo, 72, was arrested on Tuesday outside the Sacramento-area home where he has lived for at least two decades, not far from the first of eight murders he is charged with committing 40 years ago.
DeAngelo is suspected in a dozen slayings as well as 50 rapes and scores of home invasions in a crime spree that spanned 10 years and 10 California counties during the 1970s and 1980s.
Announcing his arrest on Wednesday, authorities said his name had never surfaced as a suspect prior to a major break in the case during the past week. They said a DNA match was made tying the suspect to a number of the crimes.
But officials initially did not disclose how their investigation led to DeAngelo, whose DNA had never been collected and entered into a law enforcement database.
Steve Grippi, the chief deputy district attorney for Sacramento County, on Thursday said detectives narrowed their search by using genetic information available through commercial genealogy websites that consumers use to explore their ancestry.
Confirming details first reported by the Sacramento Bee newspaper, Grippi said investigators compared DNA samples left by the perpetrator at a crime scene to genetic profiles on the ancestry sites, looking for similarities.
He did not address whether the websites volunteered the information or were ordered to provide it.
Detectives followed the family trees of close matches, seeking people who might be the killer. The process produced a promising lead a week ago, when the DNA of a relative pointed to DeAngelo based on his age and the fact that he lived near where the attacks occurred, according to Grippi.
Investigators placed DeAngelo under surveillance and obtained his DNA from an unspecified object that he discarded, which matched the crime-scene sample. A second, more decisive sample was collected days later and came back as a positive match on Monday evening, leading investigators to make an arrest the following night, Grippi said.
DeAngelo is scheduled to make his first court appearance in Sacramento County Superior Court on Friday afternoon, facing two counts of murder there.
Reporting by Fred Greaves
Recommended Video: