The banker Roberto Calvi was strangled and strung up from Blackfriars Bridge in London 21 years ago as a warning from the Mafia, detectives believe.
City of London Police are understood to have also concluded that Calvi, who was known as "God's banker" because of his links to the Vatican, was killed because he allegedly stole Mafia money and knew too much about corrupt Italian politicians. British police reopened the case in September and a month later the Italian authorities charged three men and a woman with the 62-year-old's murder.
Calvi was found in June 1982 hanging from scaffolding on the bridge over the Thames with orange rope tied into a lover's knot around his neck. He was weighed down by bricks and had $15,000 (£8,600) in cash in his pockets.
An inquest recorded a verdict of suicide, but a second inquest recorded an open verdict.
New evidence is understood to show that Calvi was almost certainly strangled close to the bridge. He was certainly unconscious, and probably dead, when he was strung up, specialists believe.
Calvi is thought to have been killed because of the Mafia money he is believed to have stolen from Banco Ambrosiano, once Italy's biggest privately owned bank. He is thought to have been ready to blow the whistle on corrupt Italian politicians.
The case took a further twist yesterday when a woman aged 42 from west London was arrested on suspicion of conspiring to pervert the course of justice and perjury. She is understood to have been questioned about evidence she gave at the second inquest.
The woman, who was released on bail until February, provided an alibi for Flavio Carboni, one of the four people charged with the banker's murder. The other three are Pippo Calo, Ernesto Diotallevi, and Carboni's Austrian girlfriend Manuela Kleinszig.
Calvi's family believes his death was linked to an organised crime conspiracy. The financier disappeared while in Italy during an investigation into Banco Ambrosiano, which subsequently collapsed with huge debts.
Detective Superintendent Trevor Smith, the senior investigating officer on the case, who recently returned from Italy, said: "We have been applying 21st-century forensic and investigative techniques to a 21-year-old crime and we having been working closely with our Italian counterparts."