Italy's anti-Mafia police are looking into the theft of files from the UK coroner re-examining the death of the man dubbed God's Banker, Roberto Calvi.
Roberto Calvi fled Italy after his bank collapsed
City of London coroner Paul Matthews had a laptop and a bag stolen in Rome.
Italian police suspect the mafia.
Calvi was found hanged under London's Blackfriars Bridge in 1982. A first inquest returned a suicide verdict.
Last September, City of London police reopened their investigation as a murder probe alongside Italian police.
The force insists that no "sensitive material" relating to the case was stolen.
A spokesman stressed that no witness statements or investigative reports were among the material taken.
But anti-Mafia officials in Rome are understood to be looking at the
possibility that Mr Matthews was deliberately targeted by the Mafia.
City of London police say they have "not yet taken a view" on the thefts.
"We are aware of the thefts.. We are working with the Italian authorities in relation to them and the Calvi case as a whole," the spokesman added.
Mr Matthews was in the Italian capital for a lecture and was not there to
discuss the case, as has been reported.
His computer laptop was taken from his hotel room and his bag was snatched as he walked through a busy station.
Nicknamed God's Banker because of his Vatican connections, Calvi fled Italy after the private bank of which he was chairman collapsed.
He arrived in London on bail, having been convicted of corruption in Italy.
In June 1982, he was found hanging from scaffolding beneath Blackfriars Bridge with bricks in his pockets and $15,000 on him.
At first he was thought to have committed suicide, but Italian police believe he was murdered by the Mafia as punishment for pocketing money they had asked him to launder.
1971: Calvi becomes chairman of Banco Ambrosiano
1981: Convicted of currency violations, but bailed pending appeal
11 Jun 1982: Leaves Italy, on a false passport, with a suitcase full of documents
18 Jun 1982: Body found beneath Blackfriars Bridge
Jul 1982: Suicide verdict at first inquest
Jul 1983: Open verdict at second inquest
1998: Calvi's body exhumed
Oct 2002: Forensic report confirms Calvi was murdered
Mar 2004: Four defendants appear at pre-trial hearing in Rome
A German panel of forensic experts, rejected the suicide theory concluding that Calvi could not have got up the scaffold under the bridge to hang himself.
The original inquest verdict of suicide was set aside and a second in July 1983 recorded and open verdict.
Four men charged with Calvi's murder are due to stand trial in Italy.