California Department of Corrections and Rehabilitation (CDCR) officials are investigating the May 20, 2023 death of an incarcerated person at High Desert State Prison (HDSP) as a homicide.
At approximately 6:40 p.m., HDSP staff observed incarcerated people Pedro Ayon and Brandon Martinez assaulting Jeffrey Concepcion on the institution’s C yard. Staff quickly responded and quelled the incident.
Concepcion was unresponsive and staff quickly initiated life-saving measures. They summoned emergency services and transported Concepcion to the institution’s triage and treatment area. He was pronounced deceased by the Lassen County Coroner at 7:45 p.m. No staff or other incarcerated persons reported any injuries.
Ayon and Martinez have been placed into Restricted Housing. Officials have limited movement on the housing unit where the attack occurred to facilitate the investigation being conducted by HDSP’s Investigative Services Unit, the Lassen County District Attorney’s Office, and the Lassen County Coroner. The Office of the Inspector General was notified, and the Lassen County Coroner will determine Concepcion’s official cause of death.
Concepcion, 43, was sentenced to CDCR on July 26, 1999, from Monterey County to serve a life sentence without the possibility of parole for first-degree murder, second-degree robbery, and attempted second-degree murder. He was received by CDCR in July 1999.
Ayon, 30, was sentenced to CDCR on June 20, 2012, from Tulare County to serve a 27-year and two-month sentence for two counts of second-degree murder, one count of assault with force likely to produce GBI, one count of second-degree robbery, and one count of attempted carjacking. He was transferred to CDCR custody on Jun. 21, 2012.
Martinez, 25, was sentenced to CDCR on April 18, 2016, from Yuba County to serve an 18-year and eight-month sentence for one count of assault with force likely to produce GBI, one count of second-degree robbery, and assault with a deadly weapon. He was transferred to CDCR custody on Apr. 21, 2016.
