SUSANVILLE, Calif. — Police are launching a homicide investigation after an inmate who was attacked by his cellmate at a prison north of Sacramento last month has died.

State prison authorities say 54-year-old Martin Hall, the victim of the attack at the High Desert State Prison in Susanville, died Wednesday.

In a news release Thursday they say Hall was attacked by 51-year-old Donald Wilson on August 31 in the cell they shared.

High Desert State Prison officials began investigating the incident last month and are now joined by the Lassen County Sheriff and the Lassen County District Attorney’s Office.

Authorities say Hall was taken to a local medical facility for treatment after the attack but died from his injuries.

He went to the Northern California prison from Los Angeles County in 2000.