Michael Gargiulo, nicknamed the "Hollywood Ripper", has been found guilty of murdering two women.
Prosecutors in Los Angeles painted Gargiulo, 43, as a "stone-cold serial killer" who preyed on women in planned attacks.
He was also found guilty of attempting to kill a 26-year-old in 2008, who survived and testified against him, APA reports citing BBC.
Actor Ashton Kutcher also testified, having arranged a date with one of the victims on the night she was killed.
In 2001, Mr Kutcher knocked on the door of 22-year old Ashley Ellerin, received no answer, and assumed his date had left for the night because he was late, he told the court in May.
But he recalled looking in the window and seeing what he had thought were red wine stains, he said.
Ms Ellerin was discovered dead the next morning by her roommate, having been stabbed dozens of times.