SEATTLE (AP) — A 25-year-old man has been charged with first-degree murder in his mother’s slaying on Christmas Day.

Mason County Prosecuting Attorney Michael Dorcy charged William Foster Thursday.

Sheriff’s deputies in Mason County say Foster stabbed and beat his mother to death Tuesday because he believed the 62-year-old woman was a demon.

According to documents, Foster lived with his mother, Claudia Foster, in Hoodsport near Hood Canal. Police say he arrived at the nearby home of a family member later Tuesday covered in blood and saying he “just slayed the demon.”

Documents say sheriff’s deputies found Foster’s mother dead at her home.

A judge Wednesday ordered Foster held on $500,000 bail.