I copied (below) a portion of an article from "AmericanMafia.com" :

In 1983, Angelo Lonardo, 72, one-time Cleveland Mafia boss, turned government informant. He shocked family, friends, law enforcement officers and particularly, criminal associates with his decision which was made after being sentenced to life plus 103 years for drug and racketeering convictions. The sentence came after the monumental investigation into the murder of Danny Greene. As a direct result of Danny's murder, Jimmy "Weasel" Fratianno also defected and co-authored The Last Mafioso and Vengeance is Mine. His courtroom testimony and that of Angelo Lonardo, once called "the highest ranking mobster ever to testify for the government" helped put away mob bosses Anthony "Fat Tony" Salerno of New York's Genovese Mafia family, Anthony "Tony Ducks" Corallo of the Luchesse clan and Carmine Persico of the Colombo family.