- "Well, I'm sure he thought it was his turf. After all, Don Leo's family has operated in Gotham for years."
Don Leo was an old crime boss and art enthusiast who operated in Gotham City. He was a member of the Leo crime family, who operated in Gotham for years. After attempting to muscle in on the turf of the Joker, the crime boss abducted him and took him to Marin Hotel for torture. Leo was killed by Joker in the hotel, and a note was pinned to his corpse by knife that told Leo's goons that they now worked for the Joker.
In 2016, Don Leo attempted to encroach on the Joker's territory in Gotham. For this he was captured by Joker himself and taken to the Marin Hotel where the Clown Prince of Crime and his girlfriend Harley Quinn were staying. Joker taunted Don Leo and explained his plans to take over the criminal underworld with Harley at his side. The Joker was prepared to brutally bash in Don Leo's skull with Harley's baseball bat, but she stopped him and gave Joker the idea to instead torture and kill Leo but leave him in one piece so that his body could send a message to other crime bosses in Gotham. Leo was killed by the Joker, who beat him to death and left a message pinned to his chest that was addressed to Don Leo's associates and read: "Boys! You work for the Joker now!"