Thomas J. Sullivan, a Pennsylvania State Constable, was shot and killed on July 12, 1907, after he and a fellow officer confronted two burglars in East Pittsburgh. Sullivan apprehended one of the suspects and was escorting him to the police station when the man pulled a gun and shot him.
Both men fled and were never apprehended.
State Killings in the Steel City: The History of the Death Penalty in Pittsburgh 