By Christian Fraser
BBC News, Rome
After 25 years, two inquests and a very lengthy trial - the mystery remains.
The verdict of the court was that Roberto Calvi was murdered - but the evidence against the five accused, said the judge, was insufficient and at times contradictory.
Calvi's body was found hanging from a London bridge in 1982
Despite the various motives put forward it seems the jury was not convinced with what, in the end, was a very complicated plot.
The proceedings in court lasted less than five minutes. Among the defendants, there was of course quiet celebration.
But this will come as a huge disappointment to the Calvi family, particularly his son Carlo, who had campaigned for the case to be re-opened.
As chairman of Banco Ambrosiano, Roberto Calvi was involved in some very sensitive financial transactions.
In his time he had worked for the Vatican bank, the Mafia, and the Freemasons. But in June 1982 when his bank collapsed - with debts of $1.5bn (£750m) - he suddenly found himself with very powerful enemies.
One of the key defendants in this case was Giuseppe Calo, a convicted mobster who in the 1980s had been the chief cashier of the Sicilian Mafia, the Cosa Nostra.
The prosecution argued that Calo had ordered the killing, angry that Calvi had lost the Mafia's money and worried he might reveal all the secrets.
But defence lawyer Renato Borzone, who defended another of the accused, Flavio Carboni, said there was no evidence to suggest the Mafia were ever involved.
"I still maintain it was suicide," he said. "But if it was murder, there was never any evidence to suspect my client's involvement - or indeed that of the Mafia."
For a large part of the two years this case has run for, it has played out in front of an empty courtroom.
The truth is, here in Italy, the death of "God's banker" is no longer the sensation it once was.
For a lot of people this trial was an uncomfortable reminder of a dark and violent period many would prefer to forget.
The prosecution said that together with the other four other defendants - three businessman and a woman - Calo had lured Calvi to London into the hands of the Mafia.
The defence said there was no evidence of Mafia involvement
Calo, who gave evidence from his high security prison, denied this charge on Tuesday in his final submissions.
"I had no interest in killing Calvi," he said.
"I didn't have the time, nor the inclination. Besides, if I had wanted him dead do you not think I would have picked my own people to do the job?"
In fact, Calo's defence argued there were others who had wanted Calvi silenced.
Philip Willan, author of a book on the trial, The Last Supper, says the suspicions still fall on some within the Vatican.
"The church does not come out of this well," he said. "And it's lucky for them that people lost interest in this trial a long time ago.
"The defence lawyer for Giuseppe Calo argued that evidence from the Calvi family suggested the banker was frightened of the Vatican, was in conflict with the Vatican, and was almost certainly trying to blackmail people in the Vatican," Mr Willan says.
Calvi's son Carlo hoped the trial would shed light on what happened
"The lawyer for Calo said the Vatican had an entirely plausible motive for killing him."
Banco Ambrosiano had a Catholic history.
In fact it was suggested by the defence, during this trial, that through offshore accounts Mr Calvi had been sending money to Poland to help fund the pro-democracy Solidarity movement - a cause supported by Pope John Paul II.
But Mr Calvi was also working for the mafia and a rather shadowy group of Freemasons, called P2, which had existed here in Italy as a counterbalance to the many communist interests which prevailed.
In short Mr Calvi was involved with some very sensitive operations.
One thing we know is that he had many secrets.
Philip Willan says: "This was a man who was supposed to keep his silence. And with an investigation pending - he was threatening not too. There were plenty who wanted him dead."