ROCKLAND (AP) — A Maine man charged with murdering one fellow state prison inmate and assaulting another has pleaded not guilty by reason of insanity.

WABI-TV reports that 42-year-old Guy Hunnewell is accused of killing 57-year-old Alan Powell in June and assaulting James Brensinger in January. He pleaded not guilty to both charges Friday, while also pleading not guilty by reason of insanity.

Hunnewell is serving a 40-year sentence for killing his girlfriend.