The Italian courts are preparing to rule on whether four people should face trial for conspiracy to murder the Vatican banker, Roberto Calvi.
Calvi's murder is one of the most intriguing mysteries of the 1980s
A BBC Radio 4 documentary meets the investigator who has played a central role in the case.
Private investigator Jeff Katz took on the most dangerous job of his life when he agreed to work for Roberto Calvi's family, to re-examine how the wealthy Italian met his death.
Nicknamed God's banker because of his Vatican connections, Calvi was found hanging under London's Blackfriars Bridge in 1982. He was weighed down by bricks and had more than £7,000 stuffed in his pockets.
Calvi had fled to the UK from Italy after the collapse of the Vatican-controlled Banco Ambrosiano, of which he was chairman. It owed in the region of $1.4 bn.
Initially, Calvi's death was dismissed as suicide; now, an Italian court is preparing to decide whether or not four people should be tried for conspiracy to murder.
'Mouth of the wolf'
And, perhaps with no small thanks to Katz, last September City of London police reopened their investigation as a murder probe alongside Italian authorities.
The extraordinary details of Katz's investigation, which began in 1991, can be heard in a BBC Radio 4 documentary, "It's my story: Mafia, masons and murder".
Jeff Katz became an investigator after working as a journalist
"When I started making inquiries through contacts in Italy," recalls Bronx-born Katz, "the answer came back that if we were to take this particular case on it would be like dancing in the mouth of the wolf."
His persistence with witnesses, some of whom had come into contact with Calvi in the hours before his death, led to the gathering of testimony which some say is crucial in proving that Calvi was murdered.
The findings also raise new questions about the role of the mafia in the case.
This is further reflected in a rare interview with the public prosecutor in charge of the investigation, Luca Tescaroli.
"Calvi was murdered as a punishment for pocketing money that Sicilian mafia and the Camorra had asked him to launder," Tescaroli tells the programme.
"He threatened to tell everything."
The documentary also tells how the police investigation in London has drawn on a reconstruction of the last few hours of Calvi's life, devised by Katz and forensic expert Angela Gallop.
Calvi's body was found hanging under Blackfriars Bridge
They painstakingly assembled a model of the scaffolding that Calvi was hung from, and conducted experiments clambering over it in pairs of Calvi's own shoes brought over from Italy.
The action, they found, would have left rust on Calvi's shoes but forensic research had found no such damage to his footwear.
A judge will decide at the end of March whether four defendants should stand trial for Calvi's murder. They all deny any involvement with it and investigations are continuing into other suspects.
Both the Vatican and the City of London Police refused to be interviewed for the programme.
Mafia, masons and murder: BBC Radio 4, Thursday, 6 January, 2005 at 2000 GMT.