By AP

California prison officials are investigating the recent death of a Soledad prison inmate as a homicide.

Department of Corrections and Rehabilitation officials made the announcement Thursday after receiving an autopsy report.

Rick Stockton, 52, was found unconscious in a bathroom at the medium-security Correctional Training Facility on Sunday. He was declared dead at an outside hospital shortly afterward. CDCR didn’t disclose the cause of death.

Stockton entered the prison system on August 1999 from El Dorado County, where he was convicted of possession of a deadly weapon, grand theft, robbery, and forgery. He was serving a sentence of 25-year-to-life.