California prison officials are investigating the death of an incarcerated man at Kern Valley State Prison as a homicide after a violent confrontation between two cellmates Saturday morning.
The incident occurred around 10:20 a.m. on July 11, when custody staff saw two incarcerated men fighting inside their cell, according to the California Department of Corrections and Rehabilitation.
Officials said staff immediately sounded an alarm and ordered the men, identified as 39-year-old Jovanny Mendez and 41-year-old Sergio Villalobos, to get down.
Sergio Villalobos, 41, was reportedly killed in a fight with his Kern Valley State Prison cellmate on July 11, 2026. (CDCR)
Mendez did not comply with orders, prompting officers to deploy pepper spray to stop the attack, officials said.
Staff called 911 and began life-saving measures on Villalobos before transferring him to the prison triage and treatment area. Despite the efforts, he was pronounced dead by medical personnel at 10:55 a.m., prison officials said.
Mendez was restrained and removed from the cell. He was transferred to restricted housing, where he will remain while the Kern Valley State Prison Investigative Services Unit and the Kern County District Attorney’s Office investigate the killing.
Jovanny Mendez, 39, incarcerated at Kern Valley State Prison is being held in restrictive housing while authorities investigate the death of his cellmate after a fight on July 11, 2026. (CDCR)
Officials said two inmate-manufactured weapons were recovered from the cell. The California Office of the Inspector General has also been notified.
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Villalobos was most recently admitted to the state prison system from Los Angeles County on Aug. 18, 2014. He was serving a life sentence with the possibility of parole following a first-degree murder conviction, CDCR said.
Mendez entered state custody from Orange County on May 24, 2017. He is serving a 14-year prison sentence after being convicted of assault with a firearm, with a firearm-use enhancement.
Kern Valley State Prison, which opened in 2005, houses more than 3,200 minimum- and high-security incarcerated people and employs approximately 1,600 staff members.
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