Casillo was highly trusted and soon rose to become the deputy and main military chief of crime boss, Raffaele Cutolo, during the period when he was imprisoned in the prisons of Poggioreale and Ascoli Piceno.

[2] In June 1996, the Sicilian Mafia pentito, Francesco Di Carlo claimed that Vincenzo Casillo together with another Camorrista, Sergio Vaccari were responsible for the murder of Roberto Calvi, the chairman of Banco Ambrosiano who was dubbed the "God's Banker".

[4] Casillo also played an active role in negotiating the release of the Christian Democrat (DC) politician Ciro Cirillo, who had been kidnapped on April 27, 1981 by the Red Brigades.

In a meeting held in April 1982, nine months after the kidnapping, Vincenzo Casillo reportedly told Giuliano Granata, the DC mayor who had taken part with him in the negotiations: "You did what you wanted and then washed your hands".

The fact that a secret service card that could be used by Casillo was found in his burnt-out car lends some credibility to the scenario that his death might have been linked to the Cirillo kidnapping.

Nicola Nuzzo, a key Nuova Camorra Organizzata member involved in the negotiations was battered to death in the ward of a Roman hospital in 1986, soon after a meeting with Carlo Alemi, the magistrate who was investigating the Ciro Cirillo release case.

Salvatore Imperatrice, Casillo's bodyguard and also a member of the Nuova Camorra Organizzata negotiating team, died of mysterious causes – alleged by authorities to be suicide, in a mental asylum in March 1989.