SUSANVILLE, Lassen County (CBS SF) — The death of an inmate at High Desert State Prison in Lassan County is being investigated as a possible homicide, and the man’s cellmate was identified as a suspect, corrections officials said.

The California Department of Corrections and Rehabilitation (CDCR) said an inmate alerted prison staffers Monday at around 11:30 p.m. that his cellmate was unresponsive. Staffers began life-saving measures and transported the inmate to the prison’s treatment and triage area where he was pronounced dead.

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Erik Montes (CDCR)

The deceased man’s cellmate, Erik Montes, was named as a suspect in his death and was rehoused in the prison’s segregated unit pending the outcome of the investigation.

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Montes was sentenced in San Mateo County in 2016 to a 28-year sentence for second-degree attempted murder with enhancements of being in a street gang and inflicting great bodily injury. He also was sentenced to a year for an in-prison offense of possessing or manufacturing a weapon.

The unidentified victim was sentenced in San Francisco in 2016 to a seven-year term for assault with a firearm.

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The prison’s Investigative Services Unit and the Lassen County Sheriff’s Office are investigating the death and thhe Office of the Inspector General has been notified, the CDCR said.