LOS ANGELES — A jury on Thursday found an aspiring actor who was described by prosecutors as a serial killer guilty of fatally stabbing two women and attempting to kill a third in their Southern California homes.

After three days of deliberations, the Los Angeles jury reached the verdict against 43-year-old Michael Gargiulo, who is also awaiting trial for a similar killing in Illinois in 1993.

Gargiulo was convicted in the murder of 22-year-old Ashley Ellerin, in her Hollywood home in 2001 on a night when she was supposed to have drinks with Ashton Kutcher, who testified at the trial. Her father sat in court for the verdict,

Gargiulo was also convicted of the 2005 murder of 32-year old Maria Bruno in her El Monte home, and with the 2008 attempted murder of Michelle Murphy, who fought off her attacker in her Santa Monica apartment and forced him to flee.

Jurors also found that Gargiulo was guilty of several special-circumstance allegations, including lying in wait and multiple murders, that make him eligible for the death penalty or life in prison with no possibility of parole.

A final phase of the trial is set to start Tuesday, with jurors to determine whether Gargiulo was sane at the time of the killings.

In Illinois, Gargiulo also faces a murder charge over the death of 18-year-old Tricia Pacaccio, who was found stabbed to death at her Glenview home in 1993. Illinois prosecutors have to wait until the completion of his trial in California before moving forward with their case against him.

Gargiulo sat in court in a lavender dress shirt and slacks with eight sheriff’s deputies standing behind him. He showed no reaction as the clerk read the verdict.

His attorneys declined comment outside court. Prosecutors and victims’ family members did not speak to reporters.

A native of the Chicago area who moved to Los Angeles in the late 1990s, Gargiulo had acting aspirations and worked as an air conditioning repair man and Hollywood nightclub bouncer at the time of the attacks.

With little physical evidence tying him to the scenes of two murders, prosecutors urged jurors to look at the cases connectively, citing uncannily similar patterns in attacks that were all in places near his residence at the time. They dubbed him the “Boy Next Door Killer.”

Allowed to cite evidence from the Illinois case, they said all four attacks were the work of a skilled serial killer who studied the lives, homes and habits of victims that he stabbed quickly, powerfully and repeatedly with a knife that he knew how to use, and studied ways to cover his tracks.

“Those similarities point to one man, one killer: Michael Gargiulo,” Deputy District Attorney Garrett Dameron said during closing arguments.

The defense relied heavily on the lack of forensic or eyewitness evidence putting Gargiulo at the scenes of the killings of Ellerin and Bruno. A shoe-covering bootie with Bruno’s blood and Gargiulo’s DNA was found near her apartment in a complex where they both lived.

“It’s incomprehensible to me that you can make a case against someone when you can’t even prove where they were,” defense attorney Dale Rubin said during closing arguments.

Gargiulo’s attorneys suggested that both women were killed by the last men who saw them alive: Bruno by her estranged husband, Ellerin by her apartment manager, with whom she’d had a sexual relationship.

Gargiulo’s attorney Daniel Nardoni suggested that the apartment manager was driven to a jealous rage because of Ellerin’s upcoming date with Kutcher.

Kutcher, who in 2001 was a rising star of “That ’70s Show” but not yet a household name, testified early in the trial that he and Ellerin were just getting to know each other and had made plans to go out together for drinks, but he arrived at her Hollywood home very late and assumed she had gone out without him when he got no answer at the door.

“I remember the next day, after I heard about what happened, I went to the detectives and said, ‘My fingerprints are on the door,’” Kutcher testified. “I was freaking out.”

The first and most important witness in the case was Murphy, a fitness buff who fought off the much larger Gargiulo in 2008 and caused him to cut himself, leaving a trail of blood as he fled. That physical evidence against him was so overwhelming that defense attorneys conceded that it was him, though they argued his mental state was such that he did not know what he was doing.

In the prosecution’s closing argument, Dameron praised Murphy, whose resistance against Gargiulo led to his arrest in all of the other cases as they grew increasingly cold.

“Michelle Murphy, because of her strength and courage, allowed investigators to work backwards,” Dameron said. “This case begins and ends with Michelle Murphy.”

The Chicago Sun-Times contributed to this story.