Authories are investigating the death of Bobby Augustus Davis, who was found unresponsive in his cell Sunday morning at Kern Valley State Prison.

According to California State Corrections spokesperson Terry Thornton, Davis’s death is being investigated as a suicide. Davis is notorious as the surviving shooter in The Newhall Incident, which changed the face of law enforcement forever.

Lt. Xavier Cano, spokesperson for Kern Valley Prison, said that Davis was a part of the “sensitive needs” program, and had been transferred to their facility for that reason.  The program serves inmates who cannot function as part of the general prison population. Davis had spent time in Folsom State Prison and Pelican Bay State Prison, where some of California’s most violent criminals are behind bars.

On April 6, 1970, Davis and Jack Twinning ambushed four California Highway Patrol Officers – James E. Pence, Jr., Roger D. Gore, Walter C. Frago and George M. Alleyn -near the intersection of Magic Mountain Parkway and The Old Road, killing all four officers. Twinning and Davis got away, with Twinning holing up in a Pico Canyon home where he battled law enforcement before killing himself.

Davis was captured, stood trial and was convicted on four counts of murder. He was sentenced to die in the gas chamber, but in 1972, the death penalty was declared cruel and unusual punishment by the California Supreme Court and his sentence was modified to four consecutive life sentences.