Once again, the authorities were largely unaware of these new events in the closed world of the Mafia until they were confirmed by Francesco Marino Mannoia (brother of Agostino Marino Mannoia) in October 1989. He had been in prison since 1985 for trafficking heroin but had been kept up to date on incidents by Agostino, who visited him regularly. According to Francesco Mannoia, his brother, Vincenzo Puccio and Puccio's two brothers were killed after Riina discovered they had been plotting to overthrow him. Giuseppe Greco and Mario Prestifilippo were apparently slain because they became too ambitious.