The discovery of bed sheets torn into strips was disclosed during the unnamed 12-year-old's trial in Superior Court in Riverside, Calif., Monday, part of testimony by Robert Geffen, a defense psychologist who had interviewed him.
The boy is accused of shooting his father, Jeff Hall, to death in 2011. Hall was a member of the neo-Nazi movement, the Riverside, Calif., Press-Enterprise reported, noting the defense is not offering a denial the boy did the shooting.
The defense attorney entered a not guilty plea by reason of insanity.
In testimony Monday, Geffen said Hall's abuse of the boy "started shortly after his birth and never let up," noting Child Protective Services had contacted the boy or his family 23 times.
Geffen added the suspect attended nine or 10 schools within four years.
The list of abuses included head-bashing incidents, belt-whippings and allegations of sexual abuse by the father and by a boyfriend of the mother, Geffen said, adding that in turn, the boy began hurting other children in school and attempted to choke a teacher when he was 8.
Chief Deputy Attorney Michael Soccio expressed concern over the torn bed sheets, saying, "He's attempted to strangle people in the past. People have used that [method] to escape, to hang themselves or to kill somebody".
2014: The Year in Music [PHOTOS]