Alleged testimony by Tommaso Buscetta, the first and one of the most authoritative of the Mafia pentiti, or turncoats, linked Mr Andreotti with the murders of the anti-Mafia carabinieri general, Alberto dalla Chiesa, and the journalist Mino Pecorelli, who both were said to know secrets about the kidnapping and murder of the former prime minister Aldo Moro.
A more recent pentito, Francesco Marino Mannoia, alleged that Mr Andreotti had met top leaders of the Mafia three times, once in Rome and twice in Sicily. He declared that he was present each time, although he did not take part in the discussions. Both pentiti gave the testimony to Italian magistrates in America, where they are now living.
The alleged evidence, 40 pages of it, was added to existing material sent by the Palermo magistrates to the Senate immunity commission only shortly before it met to debate whether to recommend lifting Mr Andreotti's immunity to allow further investigations and, if warranted, prosecution. Mr Andreotti, 74, who was prime minister seven times and a powerful leader of the Christian Democrat party for nearly half a century, is a life senator.
Mr Andreotti arrived in a bullet-proof car an hour after the session began. His defence was a 66-page memorandum drawn up by his lawyer, Odoardo Ascari, with another 10 pages containing the anti-Mafia laws passed by his governments. Buscetta, like other pentiti after him, had long refused to talk about the links between the Mafia and politics, saying that Italy was not ready to know the truth. Now, with the old political class which Mr Andreotti personified collapsing under corruption and other scandals, he and others have decided to talk. Their evidence is slowly helping to piece together some of the mysteries and crimes which have gripped Italy over recent decades.
Pecorelli was a journalist with highly dubious connections that included the conspiratorial P2 masonic lodge, of which he was a member, and the secret services, and who published highly explosive revelations in a review called Osservatore Politico. On 20 March 1979 he was shot dead in his car in a Rome street.
Buscetta told the magistrates that two top Mafia bosses had told him Pecorelli was murdered by the Mafia: 'It seems that Pecorelli was investigating political matters connected with the Moro kidnapping.
'Giulio Andreotti was worried that those secrets concerning the Moro kidnapping might come out - secrets General dalla Chiesa knew too. Pecorelli and dalla Chiesa are 'intertwined'.'
Dalla Chiesa had become a national hero by bringing the Red Brigades terrorists to justice. His appointment to Palermo, ostensibly to enable him to do the same with the Mafia, was simply a means of 'getting rid of him' Buscetta said.
Marino Mannoia told the magistrates about alleged summits between Mr Andreotti and Mafia leaders. At one, Gaetano Badalamenti, now in jail in the United States, visited him in Rome and during the meeting allegedly thanked Mr Andreotti for 'fixing' a maxi-trial of Mafia bosses.