BILLINGS, Mont. (AP) – A federal judge has rescheduled for January the trial of a man accused of killing his grandmother, cousin and cousin's boyfriend on Montana's Crow Indian Reservation.

The trial for 23-year-old Sheldon Bernard Chase was due to begin Sept. 10. He has pleaded not guilty to three counts of first-degree murder.

U.S. District Judge Richard Cebull said in an order this week that more time is needed to complete a psychiatric examination of Chase that was requested by prosecutors. The exam will determine if he is competent to stand trial.

Authorities have said Chase suffers from an unspecified mental illness.