Darst, 78, of fragile health, is likely to die in prison as jurors also found him guilty of waiting and killing a witness, which carries a life sentence.
The trial took place six years after Darst's apparent confession was broadcast by HBO documentary series, in which Darst monologues in the bathroom "What the hell did I do? σα I killed them all, of course", without realizing that his microphone was on.
Darst, who during the trial was in prison, did not appear in court to announce the decision: he was in isolation after coming into contact with a patient suffering from COVID-19.
Judge Mark Widham decided to read the verdict in Darst's absence. Speaking later to lawyers on both sides, he described the case as "the most special trial I have ever seen or heard of." His sentence will be announced on October 18.
In his closing remarks, Prosecutor John Lewin described Darst "Narcissistic psychopath" who killed Berman in an attempt to cover up the disappearance of his wife, Kathleen McCormack Darst, in New York in 1982.
Darst was tried only for the murder of Berman in California, but prosecutors say he killed three people: his missing wife, Berman, and one neighbor in Texas who discovered his identity while Darst was hiding from the authorities.