DeAngelo, 72, was charged with killing two people - Robert Offer man and Alexandria Manning - on December 30, 1979, and with the 1981 killings of Cheri Domingo and Gregory Sanchez in Goleta.
Ventura and Orange counties also have warrants out for his arrest, according to Dudley.
Each of the four new first-degree murder charges carries a possible sentence of death or life in prison without parole.
"Mr. DeAngelo is presently in custody in Sacramento", she said.
Joseph James DeAngelo, the suspected "Golden State Killer", appears in court for his arraignment on April 27, 2018, in Sacramento. The armed and masked prowler sneaked in through windows at night and surprised sleeping victims who ranged in age from 13 to 41. Authorities have charged DeAngelo with two murder counts in that case, including multiple murders enhancements and special circumstances of murder during the commission of a rape and burglary and use of a firearm.
Dudley said she is charging DeAngelo with four counts of first-degree murder with special circumstances.
He is now behind bars at the Sacramento County jail.
Cops say Joseph James DeAngelo, a 72-year-old former police officer, now faces a dozen homicide charges across the state of California.
There's now no scheduled date for DeAngelo to appear in Santa Barbara County court, Dudley said.
"This has been an ongoing discussion all district attorneys have been having, one that will not be decided tomorrow", Dudley said. He was arrested last month and remains jailed in Sacramento County.