Reopening the inquiry into the 'suicide' of 'God's banker' has exposed links with the mafia, masons and Vatican fraud, writes Nick Mathiason

The murdered man's 37-year-old son had just two questions: 'Tell me what you can do and how much will it cost?' It was the autumn of 1991 and New York investigator Jeff Katz had flown to the US city to meet the dead man's son, Carlo Calvi. It turned out that Katz could do quite a lot. Roberto Calvi, known as God's banker because of his close ties to the Vatican, was found hanging from Blackfriars Bridge, central London, with a length of orange rope woven into a lover's knot around his neck. He was weighed down by bricks and found with £15,000 in cash in his pockets....

... Calvi's death, in June 1982, was the moment the Italian underworld went overground in London. 'If you're going to take this case on it'll be like dancing in the mouth of wolves,' a secret service agent told Katz in Rome.

Katz was bitten. 'It was a fascinating case,' he said in London last week. 'It involved the mafia, the Vatican, P2 [a powerful masonic group]. It had 90 per cent of my time for two years so I was really stuck into it.' The painstaking work, carried out by the New York investigator and 30 others in the early 1990s, is now leading tantalisingly closer to the arrest of key figures in Britain and the recovery of tens of millions of pounds in what was one of the 20th century's most intriguing murders and financial scandals. The affair saw Italy's biggest private bank collapse with debts of $1.4 billion in 1982.

The City of London police working on the case today describe a mosaic of vicious mafia dons, and assets traced all over the world.

But it seems there are plenty of people who still do not want the secrets which supposedly died with Calvi 21 years ago to come to light. The Italian detective leading the investigation, Luca Tescaroli, recently received a hand-delivered letter containing black powder and two 12-volt batteries with a note saying: 'This is an ultimatum. Stop.'

But it is too late now. Evidence has come to light which is leading the investigation to four UK suspects who helped bring about Calvi's downfall. Click here to read rest of story of DEATH OF VATICAN BANKER: CASE REOPENED