Curved Yellow Fruit by VaccaD

Question 4

Mafia don Joseph "Joe Curved Yellow Fruits" Bonanno is noteworthy for having completely dropped out of sight (even to his fellow mafiosi) for two years. At the time of his disappearance, he was being investigated because of claims made by WHAT MAFIA FIGURE, who broke the code of omerta and admitted the Mafia existed, and who popularized the term La Cosa Nostra for it?