SUSANVILLE– California Department of Corrections and Rehabilitation (CDCR) officials are investigating the June 10, 2025 death of an incarcerated person at High Desert State Prison (HDSP) as a homicide.
At approximately 6:41 p.m., incarcerated person Bryan S. Cook allegedly attacked another incarcerated person, Joseph W. Reagan, in the dayroom.
Staff quickly quelled the incident and immediately initiated life-saving measures on Reagan. Reagan was taken to the prison’s triage and treatment area where he was pronounced deceased by medical staff at 7:17 p.m. No staff or additional incarcerated people were injured.
Officers recovered an inmate-manufactured weapon at the scene.
Cook was moved to restricted housing pending investigation into this case. Officials have limited movement in the area where the attack occurred to facilitate the investigation being conducted by HDSP 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 Reagan’s official cause of death.
Reagan, 44, was most recently received from Tulare County on Jan. 15, 2009. He was sentenced to serve 10 years for vehicular manslaughter, and was sentenced to additional time by Lassen County for multiple in-prison offenses, including assault with a deadly weapon.
Cook, 49, was most recently received from Imperial County on Aug. 5, 2016. He was sentenced to serve life with the possibility of parole for second-degree murder.
High Desert State Prison, which opened in 1995, houses approximately 2,900 incarcerated people at various custody levels. The facility provides educational, vocational, medical, and mental health services.
Joseph W. Reagan (deceased)
Bryan S. Cook
FOR IMMEDIATE RELEASE: June 11, 2025
CONTACT OPEC: OPEC@cdcr.ca.gov