SOLEDAD, Calif. (AP) — California officials say the death of a 19-year-old prison inmate was a homicide.

Salinas Valley State Prison officials said Tuesday that they are holding 26-year-old Alberto Cortez and 25-year-old Jaime Romero in isolation while they investigate the slaying.

Correctional officers found Jose Alcantar-Ortega lying on his cell floor Friday. He died Monday of multiple stab wounds to the head, neck and upper chest.

Investigators recovered two inmate-made weapons.

The victim was serving a 16-year San Mateo County sentence for robbery and another seven-year term for assault.

Cortez was serving a life sentence for a Monterey County murder, and an additional term for assaulting an officer and gang activity.

Romero was serving a 17-year sentence from San Mateo County for assault with a firearm and resisting a peace officer.