The mob boss who had the black market operation in Naples (not Sicily) after WWII was Vito Genovese. He did help the Allies after they landed in Sicily prior to invading the Italian mainland.
Several mob bosses died after a short time as Dons. I think you're referring to Carmine Galante, the most recent short-timer who was killed in office.
Q. Which mob boss was identified by Sen. Estes Kefauver as the top crime boss in America following his televised hearings on organized crime in 1950-51? (Hint: he wasn't Italian, and he wasn't Meyer Lansky.)