Before he was NYC mayor, he was the U.S. attorney who prosecuted the mafia in the "pizza connection" case
Rudolph W. Giuliani, who has prosecuted Mafia chieftains, millionaire ... 
Giuliani to Quit, Hints at Run for N.Y. Mayor : High-Profile U.S. Attorney's Targets 
... the month amid speculation he might run for mayor of New York City.