On March 22, 1905, while working in plainclothes in order to catch a thief who was preying on drunks and the like, Officer Mulvihill was involved in an altercation with a suspect who had just attempted to rob Mulvihill's partner, who was also in plainclothes. During the altercation, Officer Mulvihill's revolver discharged, mortally wounding him. The suspect was found hiding in an alley a short time later and was charged with Officer Mulvihill's death. The suspect was an actor with a company playing at the local theater.