Actor Ashton Kutcher testifies in trial of alleged serial killer known as the 'Hollywood Ripper'

Called to the stand in the trial of an alleged serial murderer, Ashton Kutcher testified Wednesday that he showed up in February 2001 at the Hollywood bungalow of a young fashion design student to pick her up for a date, saw what he believed was red wine spilled on the carpet and left because he thought she had already gone out for the night.

The actor -- best known for his work on the TV sitcoms "That '70s Show" and "Two and a Half Men" -- said he learned the next day what had happened to Ashley Ellerin, spoke to police and was "freaking out" because he knew his fingerprints would be on the front door of her home.

Related: Trial begins for alleged 'Hollywood Ripper'; Ashton Kutcher may be called to testify

Kutcher told the Los Angeles Superior Court jury hearing the case against Michael Gargiulo that he had last spoken to Ellerin at 8:24 p.m. on Feb. 22, 2001, to let her know that he would be late to pick her up to go out that night. He said he showed up between 10:30 p.m. and 10:45 p.m. after unsuccessfully trying to reach her several times by phone.

He said he thinks he called her four times, but probably only left two messages because he was "trying to take her on a date'' and didn't want to seem too eager.

The 41-year-old actor said he found all of the lights on inside Ellerin's home, looked through a window and didn't see anything, tried the front door only to find it locked and peered into another window and "saw what I thought was a red wine spilled on the carpet.''

"I didn't really think anything of it,'' he said, noting that she had recently hosted a party at her home.

Kutcher said that he "figured I screwed up'' by showing up to her house too late and assumed that she had gone out with a friend.

He described the 22-year-old woman as a friend with whom he had been planning to get together for dinner and drinks.

The young woman's roommate discovered her dead the next morning. She had been stabbed 47 times in the hallway outside her bathroom in an attack in which she was nearly decapitated, Deputy District Attorney Daniel Akemon told jurors in his opening statement earlier this month.

The prosecutor said Ellerin's friends had noticed earlier that Gargiulo had showed up uninvited and seemed to be "fixated" on her at a party.

Along with Ellerin's murder, Gargiulo is charged with the Dec. 1, 2005, killing of Maria Bruno in an El Monte apartment and the attempted murder of Michelle Murphy, who survived being stabbed eight times in her Santa Monica apartment in April 2008. He could face the death penalty if convicted.

The prosecutor told jurors that the evidence would show that the women were murdered by a "boy-next-door killer'' who lived near each of them and plotted to attack them with a knife in or near their homes.

Gargiulo was able to escape detection for nearly 15 years before accidentally cutting himself with a knife and leaving a "blood trail'' during the Santa Monica attack, Akemon said.

The prosecutor told jurors that they would also hear evidence about a third killing -- the Aug. 14, 1993, slaying of Tricia Pacaccio, an 18-year-old Glenview, Illinois, woman who was repeatedly stabbed on her front door step after returning home from a night out with friends. But he noted that the panel will not be asked to determine whether Gargiulo is guilty or innocent of Pacaccio's killing, telling juors that it will only be used to show motive and intent.

One of Gargiulo's attorneys, Daniel Nardoni, countered in his opening statement that the 43-year-old defendant maintains that he is innocent.

The lawyer said that his client "never admitted to killing any of these women'' despite a ``42-hour interrogation'' by undercover Los Angeles County sheriff's detectives in an El Monte jail about 11 days after he was arrested. He said his client denies killing Ellerin, Bruno or Pacaccio.

"We do not have to prove Michael Gargiulo's innocence,'' Nardoni said in his opening statement, saying that his client is presumed to be innocent.

Gargiulo was arrested in June 2008 by Santa Monica police in connection with the attack on Murphy, and was subsequently charged with the killings of Ellerin and Bruno.

The murder charges include the special circumstance allegations of multiple murders and murder by means of lying in wait, along with allegations that he used a knife in the commission of the crimes.

Authorities in Illinois charged him in 2011 with Pacaccio's slaying.

Gargiulo -- who has a 1997 felony conviction for burglary in Cook County, Illinois -- lived one block away from the high school graduate at the time of the slaying and was good friends with one of her two younger brothers, according to an arrest warrant filed in Cook County.

"We have never given up on Tricia Pacaccio or her family and their search for justice in this case,'' Cook County State's Attorney Anita Alvarez said in a statement released shortly after Gargiulo was charged in Illinois.

"It has been a very difficult and challenging investigation, but we are extremely pleased to be finally bringing this charge and hopefully providing some measure of closure to a family that has been devastated by a violent crime that no one should have to endure.''

CNS contributed to this report.