Batman: Shadow of the Bat #71

ANATOMY OF A MURDER Joe Dell is murdered at his loft next to his pigeons and gang graffiti. Using his identity as Detective Hawke, Bruce Wayne investigates the murder and then puts on his Batman costume to shake down the gang. After learning that the gang was responsible only for the graffiti and a beating of the victim, Batman narrows down his suspects until he discovers that Joe Dell was having an affair. Frank Layne the jealous husband killed Joe Dell!