Inmate beaten and killed by other inmates in California prison

A convicted murderer was killed in an attack by other inmates at a Southern California prison this week, authorities said.

Employees at the Calipatria State Prison in Imperial County witnessed the sudden death of 46-year-old Alberto Martinez in the prison yard on Thursday, authorities said.

Inmate Tyler A. Lua punched him, threw him to the ground and continued to beat him, the California Department of Corrections and Rehabilitation said in a news release.

Two other inmates, Jorge D. Negrete-Larios and Luis J. Beltran, began beating Martinez as he lay motionless, and staff “stopped the incident using pepper spray and a baton,” the department said.

The department said Martinez had “injuries consistent with an imprisoned weapon” and two such weapons were found where the attack occurred.

Medical staff attempted to treat Martinez's injuries, but he died within an hour. Prison officials say they are investigating his death as a homicide.

The Imperial County Coroner will determine the exact cause of death.

Martinez was sentenced to death in 2010 after being convicted of first-degree murder for his role in the kidnapping and murder of a man in exchange for payment by the man's sister.

Martinez described himself in court as an employee of the Mexican Mafia. He was featured in a 2023 Los Angeles Times article that detailed how members of the prison-based crime syndicate operated Use smuggled cell phones to raise money and order murders on the city streets.

Although Martinez was initially on death row, he was among the condemned prisoners moved to the general population after Gov. Gavin Newsom imposed a moratorium on executions in 2019.

According to the Department of Corrections, Martinez was also serving a life sentence for attempted first-degree murder and an additional two-year sentence for street gang activity.

The three inmates involved are being “housed in special accommodations” pending an investigation, the department said.

Lua and Negrete-Larios are both serving prison sentences for attempted second-degree murder and other convictions. Beltran was sentenced to life in prison for first-degree murder in 2023.