A murder suspect was reportedly dressed in a Halloween costume complete with a mask when he allegedly murdered his mother in the family’s northeast Manteca home.A reliable source indicated Manteca Police found a mask smeared with the blood of Kathleen Karen McGehee, 55, after they arrested her 26-year-old son Tuesday at 1:30 a.m.Dawson McGehee is charged with his mother’s murder on Halloween night and is facing arraignment this afternoon in the San Joaquin County Superior Court in Stockton at 1:30 p.m. He had been arrested by police as he was driving near North Main Street and Louise Avenue some seven hours after his mother’s body had been discovered in the family home on Golden Pond Drive.Sources revealed that the former University of the Pacific student had been under the care of a therapist for the last year because of being plagued by a demon in his head. He had worked as a waiter at the Macaroni Grill in Stockton to help with college expenses. He was living with buddies before moving back home within the last year.Dawson was reportedly told by the therapist that he had to face his fears and face life head-on in the form of exposing himself to scary movies and costumes.