ROCKLAND, Maine — A 42-year-old Maine State Prison inmate accused of killing another prisoner two weeks ago has been indicted by a Knox County grand jury.

Guy E. Hunnewell, 42, was indicted on a charge of intentional and knowing murder in connection with the June 25 death of Alan D. Powell, according to the grand jury list released Thursday.

Powell, 57, died after being attacked by Hunnewell about 6:30 p.m. that day in an exercise area at the Maine State Prison in Warren, Maine State Police said after the incident. Powell died from blunt force trauma of the head, according to the Maine medical examiner’s office.

Hunnewell also was indicted by the grand jury for aggravated assault in connection with a Jan. 28 attack against another prisoner. In that incident, Hunnewell is accused of using a shovel to injure the other prisoner.

Hunnewell is serving a 40-year prison sentence for killing his estranged girlfriend Stephanie Gilliland, 20, of Benton at his Fairfield apartment in December 1997. She suffered more than 21 stab wounds in that fatal attack.

Powell had served about 22 years of a life sentence for the June 1989 stabbing and strangulation death of Martha Daigle, 64, in her Waterville home. The victim was sexually assaulted in the fatal attack.