Batman: The Long Halloween#7(1997)

On April Fool's, Carmine Falcone hires The Riddler to solve the mystery of the Holiday killer. Riddler comes with many possible scenarios and explains that the gun used for the murders, a .22, is very light on the hand, proper for a woman, stating that his choices would be Catwoman and Carla Viti. He explains that Catwoman might be the killer because she had access to Falcone's safe and thus, she knew the places and names of the people to attack. Next, he explains that Carla Viti might be responsible because she somehow turned the whole "family business" into something personal and once she murdered her own son, she might as well keep the killing spree, knowing that she wouldn't be considered as a suspect. Meanwhile in the Batcave, Batman investigates the evidence left at every crime scene and theorizes that the killer would be Sal Maroni, as he is the only one that benefits from the death of the Falcone empire. However, Alfred suggests that the killer might be someone who pursues justice a little too far. Batman analyzes the hypotesis that James Gordon or Harvey Dent might be the holiday killer. In the end, he comes to the conclusion that Gordon couldn't have done any of the murders, but Dent could. At that moment, Dent and Gordon take the resolution to arrest Bruce Wayne for his involvement with Falcone and his dirty money, while the corrupt assistant Wells listened the conversation the whole time. In the end, Falcone is tired of The Riddler's guesses and demands him an answer under the threat of Sofia Falcone killing him if he doesn't. The Riddler says that the holiday killer is Falcone himself. The answer is so ludicrous that Falcone and Sofia laugh at him. Falcone tells his daughter to take the man out of his building and to come back when she was done. Sofia pushes Riddler out to the streets and Riddler wanders alone in a dark alley, when Holiday appears and aims his gun at him. Holiday shoots his gun several times and then he leaves the scene, not before dropping his gun and the umbrella he was carrying. Riddler is paralyzed with fear and alone, he wonders why Holiday didn't murder him.