Officer Coax and Deputy Warden John Pieper were shot and killed during an attempted prison escape at Western Penitentiary (modern-day SCI Pittsburgh). The escape attempt started when a gas main exploded near the prison's front gates. In the ensuing panic of the prisoners fleeing towards the prison's yard a guard was disarmed. The inmates used the weapon to shoot and killed Deputy Warden Pieper and Officer Coax.
Local police and deputies responded to the prison and were able to prevent the escape and assisted with bringing the situation under control. Five inmates were charged with first degree murder. Two were acquitted. Each of the other three were convicted of two counts of first degree murder. One received the death penalty and was executed December 27, 1926.