Joe Chill murdered Bruce Wayne, rather than the boy's parents. Martha Wayne was so traumatized by the event and the loss of her son that she had a mental breakdown. Her husband, Thomas, tracked Chill down and beat him to death. However, before doing do so, When Thomas returned and informs her that Chill was dead, she turned to her husband to reveal that she cut open her cheeks to create a faux smile, telling him that she was finally smiling. Thomas then had her institutionalized.
Martha escaped and turned to a life of crime, and becoming the archenemy of her husband, Batman. Her actions as Joker would cause further tragedy for Thomas as his vigilante partner Catwoman was shot through the gut and paralyzed from the waist down.