Convicted murderer killed in California prison

Jacob Kober (left); Matthew Perez (right) / California Department of Corrections and Rehabilitation

A homicide investigation is underway in the Central Valley after a convicted murderer was allegedly killed by another inmate at the Kern Valley State Prison, according to the California Department of Corrections and Rehabilitation. 

Officials said 35-year-old Jacob Kober died around half an hour after he was found unresponsive in his cell he shared with 39-year-old Matthew Perez last Thursday. 

It appeared Kober suffered "serious injuries" consistent with an "incarcerated-manufactured weapon," the CDCR said in a statement. That weapon was recovered at the scene.

Perez was also injured by a similar weapon and was taken to an outside medical facility for further treatment. He is expected to recover.

Kober's official cause of death remains under investigation.

Kober was convicted for first-degree murder in Alameda County in 2015. He was sentenced to life in prison with the possibility of parole.

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Perez was transferred from Monterey County in 2012. He was sentenced to 18 years in prison for assault with a firearm and other charges.

There were no other reported injuries.