Officer John Mills was beaten to death by three inmates in retaliation for the deaths of three inmates the previous year. All three inmates were charged with first degree murder. Two of the inmates were tried and acquitted in March of 1972. The evidence revealed that it was the third inmate who killed Officer Mills. That inmate, who was awaiting his trial at San Quentin, was shot and killed by an Officer during a prison riot that the inmate was responsible for starting on August 21, 1971.