Arizona ? A 12-year-old boy who fatally shot his mother after an argument over his chores was found guilty of premeditated murder.

Judge James Conlogue found the boy guilty after a hearing Friday in Cochise County Superior Court in the southern Arizona town of Bisbee. The boy is not being identified because he was charged as a juvenile.

Conlogue ruled that prosecutors had proved the boy acted intentionally and with premeditation when he shot Sara Madrid, 34, eight times on Aug. 1. The shooting happened after the boy had argued with his mother over his chores.