IE Man Accused Of Killing Cellmate In Detention Center

RANCHO CUCAMONGA, CA — An inmate was found unconscious in his cell on Monday after an apparent altercation with his cellmate in a Rancho Cucamonga jail, authorities said.

Around 11:12 p.m., deputies found Zacarias Joseph Ruiz in his cell with "obvious trauma." Medical staff attempted to resuscitate him and he was taken to a hospital where he was pronounced dead on Tuesday, according to the San Bernardino County Sheriff's Department.

The agency sent in its Homicide Detail to investigate, which determined that Ruiz and his cellmate, Isaiah Mark Bailon had been involved in a physical altercation before deputies found Ruiz, officials said.

Bailon, 26, of Barstow, has been in custody since Dec. 31, 2025 when he was arrested on suspicion of attempted murder and robbery. He is now facing murder charges, authorities said.

Ruiz, 38, of San Bernardino, had been arrested on May 5, 2025 on suspicion of criminal threats and domestic violence. The department says it will conduct an autopsy to find the manner and cause of death.

Anyone with information related to this case is asked to contact the Homicide Detail at 909-890-4904. Callers wishing to remain anonymous should contact We-Tip at 1-800-78-CRIME (27463) or go to wetip.com.