On February 25, 1937, Detective Sergeant Thomas Sullivan was shot and killed while he and his partner investigated a rash of fifteen robberies in the area of Pine and Olive Streets. Although their shift had finished the two detectives continued their investigation and had gone to the Leonard Hotel, 3232A Olive Street, to ask the clerk if he had seen anyone fitting the descriptions of the two suspects. The clerk took the detectives to room 209 where two such men were staying.

The men in the room cracked the door open, slammed it, and then began shooting through it. The detectives returned fire and then kicked the door in. One of the suspects was killed and Detective Sergeant Sullivan was mortally wounded. The second suspect fled but was shot and killed by other officers as he fled in a stolen car The two 19 year old suspects were escaped convicts from a Michigan state penitentiary. Detective Sergeant Sullivan had been shot five times, in the chest, the lower abdomen, left arm and with a bullet lodged in his spine, succumbed to his wounds the following day, on February 26, 1937 at 4:50 am.

Detective Sergeant Sullivan had been with the police department for 18 years, joining it after his service in the US Army during WWI. He was survived by his wife and three children. Two of his children followed in his footsteps and became St. Louis police officers. Interred: Calvary Cemetery.