Who was the first Mafia boss to turn informant ("pentito") and explain the inner workings of the organisation, who told  that Geraci took care of the fugitive Riina while he stayed in Partinico?
Nenè Geraci Antonio Geraci (Partinico, January 2, 1917 – Partinico, February 6, 2007), better known as Nenè or "il vecchio" (the old one), is the historical boss of the Mafia in Partinico, in the province of Palermo. Geraci sat on the Sicilian Mafia Commission since the mid-1970s and belonged to the hard line faction allied with the Corleonesi of Totò Riina and Bernardo Provenzano. According to the pentito Tommaso Buscetta, Geraci took care of the fugitive Riina while he stayed in Partinico.
Calogero Vizzini Calogero "Don Calò" Vizzini (July 24, 1877 – July 10, 1954) was a historical Sicilian Mafia boss of Villalba in the Province of Caltanissetta, Sicily. Vizzini was considered to be one of the most influential and legendary Mafia bosses of Sicily after World War II until his death in 1954. In the media he was often depicted as the "boss of bosses" – although such a position does not exist in the loose structure of Cosa Nostra.