Investigators who used a genealogical website to track down an ex-policeman they believe to be the shadowy serial killer and rapist who terrified California decades ago say the technique is ground-breaking.
But others say it raises troubling legal and privacy concerns for the millions of people who submit their DNA to such websites to discover their heritage.
There aren't strong privacy laws to keep police from trolling ancestry site databases, said Steve Mercer, the chief lawyer for the forensic division of the Maryland Office of the Public Defender.
"People who submit DNA for ancestors testing are unwittingly becoming genetic informants on their innocent family," Mercer said, adding that they "have fewer privacy protections than convicted offenders whose DNA is contained in regulated databanks."
Joseph James DeAngelo, 72, was arrested on Tuesday after investigators matched crime scene DNA with genetic material stored by a distant relative on an online site.
From there, they narrowed it down to the Sacramento-area grandfather using DNA obtained from material he'd discarded, Sacramento County District Attorney Anne Marie Schubert said.
Authorities declined to name the online site but two of the largest, Ancestry.com and 23andMe, said they weren't involved in the case.
DNA potentially may have played an earlier role in the case.
It was just coming into use as a criminal investigative tool in 1986 when the predator variously known as the East Area Rapist and the Golden State Killer apparently ended his decade-long wave of attacks.
DeAngelo, a former police officer, probably would have known about the new method, experts said.
"He knew police techniques," said John Jay College of Criminal Justice professor Louis Schlesinger.
"He was smart."
No one who knew DeAngelo over the decades connected him with the string of at least a dozen murders, 50 rapes and dozens of burglaries from 1976 to 1986 throughout the state.
After he was identified as the suspect, however, prosecutors rushed to charge him with eight killings.
In addition, police in the central California farming town of Visalia said Thursday that DeAngelo is a suspect in a 13th killing and about 100 burglaries in the area.
