Officer Ahern was accidentally shot and killed with his own weapon while using a patrol call box at Euclid and Fountain in the Tenth District. He threw his night stick over his shoulder, which struck the hammer on his revolver which he carried in his right hip pocket, causing it to discharge, striking him in the leg. He was expected to make a recovery at City Hospital but blood poisoning set in. He was advised that he would have to have his leg amputated in order to save his life. Officer Ahern refused the amputation and as a result died from the wound 35 days after the incident.

Officer Ahern was survived by his wife. He had been with the agency for five years and was survived by his wife. Interred: Calvary Cemetery.