A man who prosecutors say was one of California's most elusive serial killers was charged Thursday with four additional counts of murder, leaving him now facing a dozen murder charges across the state.

Joseph James DeAngelo, a 72-year-old former police officer, was charged in connection with four slayings in 1979 and 1981 in Santa Barbara County, District Attorney Joyce Dudley said at a news conference Thursday.

Authorities suspect DeAngelo killed Greg Sanchez and his girlfriend Cheri Domingo on July 27, 1981 inside a home near Goleta where Domingo had been house-sitting. Investigators said DNA from that crime scene was linked to other crimes they believe were committed by the so-called Golden State Killer.

DeAngelo has also been charged with killing Robert Offerman, an orthopedic surgeon and Alexandria Manning, a psychologist, in their condominium in December 1979.

DeAngelo now faces four counts of first-degree murder with special circumstances in Santa Barbara, though it was unclear when he might appear in court there.

He already has been charged with eight other murder counts in Sacramento, Ventura and Orange counties.

"Violent cold cases never grow cold for victims or their loved ones," Dudley said. "In fact, most of them spend their lives feverishly seeking answers and desperately hoping for justice."

Investigators suspect DeAngelo committed at least a dozen murders and more than 50 rapes across California in the 1970s and '80s.

Prosecutors said they used DNA and a genealogical website to identify DeAngelo. He was arrested last month and remains jailed in Sacramento County.

His attorney, Diane Howard, did not immediately respond Thursday to an email seeking comment.