The Bay Area man was killed last week in a California prison where he'd been serving a life sentence for murdering a close friend, officials said.

State corrections officials have launched a homicide investigation after a convicted killer from Alameda County died following an incident at a Central Valley prison Thursday evening.

Jacob Kober, 35, was stabbed multiple times in his Kern Valley State Prison cell on Thursday, authorities said. His cellmate, identified as 39-year-old Matthew Perez, also sustained injuries consistent with a “prison manufactured weapon,