Former Mafia boss of bosses Salvatore 'Totò' Riina was acquitted Tuesday of ordering a December 23, 1984 high-speed train bombing that killed 16 people and wounded 267 in an Apennine tunnel between Florence and Bologna. The motive behind the attack was to distract Italian security forces after the testimony of Cosa Nostra supergrass Tommaso Buscetta to antimafia prosecutor Giovanni Falcone had led to a series of arrest warrants in September 1984 that subsequently would lead to the Maxi Trial against 474 Mafia defendants. Mafia boss Giuseppe 'Pippo' Calò was convicted for ordering and organising the so-called 'Christmas Attack' in February 1989. In April 2011 Riina was indicted for ordering the bombing. Riina, 84, was acquitted for insufficient evidence, judicial sources said.