During the Maxi Trial in the mid-1980s, the Mafia turncoats (pentiti) Tommaso Buscetta and Salvatore Contorno said that Mangano was a uomo d'onore (man of honour) of Cosa Nostra and a member of the Porta Nuova family that was headed by Giuseppe Calò.

From 1973 to 1975, Mangano was hired as stable keeper at the Villa San Martino owned by Silvio Berlusconi in Arcore, a small town near Milan.

Mangano left spontaneously in late 1975, concerned about Berlusconi's reputation, when many newspapers started making a scandal about his stay at Arcore.

Public prosecutor Paolo Borsellino named Mangano in his last interview on 19 May 1992 with the reporters Jean Pierre Moscardo and Fabrizio Calvi.

The pentito Salvatore Cancemi disclosed that Berlusconi's company Fininvest, through Dell'Utri and Mangano, had paid Cosa Nostra ₤200 million (€100,000) annually.

According to Cancemi, the alleged contacts were to lead to legislation favourable to Cosa Nostra, in particular the harsh article 41-bis prison regime.