The "Golden State Killer" suspect has been charged with four more counts of murder in Santa Barbara County, California.
Joseph James DeAngelo, a 72-year-old former police officer, was taken into custody in late April at his home in Citrus Heights in Sacramento County, the same county where his alleged crime spree began in 1976. The crimes continued across the state until 1986.
DeAngelo faces eight other murder charges in Orange, Ventura and Sacramento counties as well.
Inside 'Golden State Killer' suspect's life in jail Suspected 'Golden State Killer' seemed shocked by arrest, told police he had a roast in the oven: Official Former police officer, 72, arrested in decades-old 'Golden State Killer' caseThe latest charges in Santa Barbara County are in the deaths of Cheri Domingo and Gregory Sanchez (Oct. 27, 1981) and Drs. Debra Manning and Robert Offerman (Dec. 30, 1979).
Santa Barbara County District Attorney Joyce Dudley said she "teared up" when she heard of DeAngelo's arrest.
"[We were] always in search of truth and justice,” Dudley said.
Officials are looking at evidence to determine whether DeAngelo can be connected to any other crimes as well.
DeAngelo, who has adult children, was a police officer in Exeter in central California from 1973 to 1976, officials said. He was then a police officer in Auburn in Northern California from 1976 to 1979 until he was fired, officials said.
DeAngelo was fired in 1979 after he allegedly stole a hammer and a can of dog repellent, The Associated Press reported, citing Auburn Journal articles from the time.
The "Golden State Killer" is believed to have killed at least 12 people and raped more than 50 people.
DeAngelo has not yet entered a plea to any of the charges against him.
ABC News' Jennifer Harrison contributed to this report.