Buscetta was the first ever Sicilian Mafiosi boss to become an informant ( pentito ) ; he revealed that the Mafia was a single organisation led by a Commission , or '' Cupola '' ( Dome ) , thereby establishing that the top tier of Mafia members were complicit in all the organisation 's crimes . In an attempt to divert investigative resources away from Buscetta 's key revelations , Riina ordered a terrorist-style atrocity , the 23 December 1984 Train 904 bombing ; 17 people were killed and 267 wounded . It became known as the ' Christmas Massacre ' ( Strage di Natale ) and was initially attributed to political extremists . It was only several years later , when police stumbled on explosives of the same type as used in Train 904 while searching the hideout of Giuseppe Calò , that it became apparent that the Mafia had been behind the attack
Train 904 bombing
Train 904 bombing
Salvatore Riina