An Arizona judge last week found a 12-year-old boy guilty of murdering his mother after the two got into an argument over chores.

The Cochise County Superior Court judge ruled prosecutors showed the boy acted intentionally when he shot his mother, Sara Madrid, eight times last year. He was found guilty of premeditated murder.

The boy, who has not been identified because of his age, is scheduled to be sentenced on Jan. 23.

Madrid, 34, was found shot outside her home last August. The boy's lawyer argued that he did not intend to kill Madrid, and that he was acting out in response to both verbal and physical abuse at the hands of his mother, the Arizona Republic reported.

According to court testimony, Madrid and the boy got into an argument over his chores. Madrid left the house briefly.

The boy got a .22-caliber pistol from Madrid's closet and waited for her to return outside their house. When she came home, he repeatedly shot her.

Madrid's live-in boyfriend of 10 years, Alfonso Munoz, witnessed the shooting and said the boy handed him the empty gun.

Munoz said he taught the boy how to shoot the gun, but told him it was only for emergencies and home protection.

Prosecutors wanted to try the boy as an adult, but Judge James Conlogue ruled the case should remain in juvenile court after hearing testimony from a psychiatrist and a psychologist that the boy suffered verbal and physical abuse.

They also argued he could be rehabilitated in the juvenile justice system.

Madrid's sister backed up the testimony, and said Madrid never wanted the boy to live with her. The sister said Madrid referred to the boy as "stupid and dumb."