CUMBERLAND, Md. — Maryland State Police say an inmate who was found unresponsive in a Cumberland prison was strangled and his death has been ruled a homicide.

Fifty-seven-year-old Lewis J. Thompson Jr. was found in his cell at the North Branch Correctional Institution on Dec. 8 and pronounced dead at a local hospital.

Thompson was serving a 40-year sentence on a rape charge for which he was found guilty in Anne Arundel County in 1987, according to online court records.

The Herald-Mail of Hagerstown reports that state police are conducting the investigation into Thompson’s death. No charges have been filed yet.