Officer William McCormack was shot and killed while assigned to a cigar store that had recently been robbed. Officer McCormack was in a back room of the store when two robbers entered. One of the robbers took the clerk from the counter as the second went behind the counter and started to remove money from the register. As he did so he spotted Officer McCormack and opened fire, striking him in the neck. Officer McCormack never saw or heard the suspects enter the store and was unaware the robbery was taking place.

Four men were implicated in the murder of Officer McCormack. Three were apprehended and sentenced to life for murder. The actual killer was found to be in the Idaho Penitentiary almost two years later. He was returned to Missouri, convicted of murder, and sentenced to life. One of the others was paroled on January 31, 1936, and another on December 29, 1936.

Officer McCormack had been with the agency for 35 years and was survived by his wife and daughter.