Complex sentence: Grimaldi tells Karch that he had learned that the crime had been planned by Leo Renfro in league with the Chicago Mafia; a Chicago gangster had ruined Karch's father's career as a magician and opening act in Vegas.
Split into simpler sentences: Grimaldi tells Karch that he had learned that the crime had been planned by Leo Renfro in league with the Chicago Mafia. A Chicago gangster had ruined Karch's father's career as a magician and opening act in Vegas.