Ashton Kutcher is set to testify in a trial against Michael Thomas Gargiulo, who is accused of murdering his then-girlfriend Ashley Ellerin.
Ellerin, who was just 22 when she was killed on February 21st in 2001, was in the shower before being stabbed 47 times as per court documents and the doctors said that her throat was slashed violently that the killer nearly decapitated her, the Mirror reported.
Gargiulo, who is accused of murdering four victims, moved from Chicago to Los Angeles and lived just 400 feet from Ellerin.
The serial killer is also accused of the murder of Maria Bruno, who had moved into a home just 100 feet from him shortly before she was killed on December 1, 2005.
The 36-year-old actor was reported to have given evidence at the time of Ellerin's death, having arrived at 10:45 to go out together but she never answered the calls.
In an interview on 48 Hours Mystery, which aired in 2012, it was reported that Ashton told police that he looked into windows and saw what he thought was wine on the floor and left before her body was discovered by her flatmate the following day.