US Attorney General Bill Barr flew to Italy to hear the secret tapes of a Maltese professor who helped kickstart the probe into alleged Russian interference in the 2016 US election, according to a report.
Mr Barr and investigator John Durham flew to Italy after asking the secret service to hand over any information they had on Professor Joseph Mifsud, the Daily Beast reported.
They suspected the former University of Malta professor was an Italian or British-run spy.
While in Rome last week, they heard a taped deposition from Prof. Mifsud explaining why he was in danger and saw Italian records showing had had applied for police protection.
The Mueller Report, first published in April, revealed how investigators spoke to Prof. Mifsud at a Washington Hotel lobby in February 2017.
He reportedly told the Trump campaign in April 2016 that Russia had “dirt” on then candidate Hillary Clinton in the form of “thousands of e-mails”.
Prof. Mifsud was working at Rome's Link Campus University until 2017, when Trump campaign adviser George Papadopoulos was jailed for lying to the FBI.
Mr Papadopoulos's allegation that several "spies" had been sent to entrap him gained currency in Trump's White House.
Prof. Mifsud dropped off the radar, but the Italian daily Corriere della Sera said he was holed up in an apartment owned by a company with ties to Link Campus until May 2018.
Link Campus has close relations with both the intelligence services community and Italy's anti-establishment Five Star Movement (M5S), part of the ruling coalition, the newspaper said.
Mr Barr and investigator John Durham "warned" spy chief Gennaro Vecchione that the US is concerned the ties between Link and leading M5S figures - including Foreign Minister Luigi Di Maio - could affect Italy's willingness to cooperate, the La Repubblica daily said.
Italy's Parliament will launch an investigation into the meetings between Mr Barr and the secret services, the Corriere and Messaggero reported, saying his repeated calls for information looked like "an attempt to pressure Italy".
In an interview with La Repubblica, Prof. Mifsud previously denied having anything to do with the Kremlin.
The CNN reported in 2017 that Prof. Mifsud was no longer turning up for work at the private university in Rome where he lectured.
In September last year, a judgement issued by a Sicilian court revealed that Italian police had tried and failed to track him down to serve him notice of court action filed against him by the University Consortium of Agrigento, where he once served as president.
Palermo’s court of auditors found him guilty of receiving overpayments and ordered him to pay back more than €49,000 to the University consortium.
Prof. Mifsud’s name surfaced again on Wednesday following media reports that Italy’s prime minister Giuseppe Conte gave permission for a top US official to meet Rome's intelligence services as part of Trump-lead efforts to discredit claims he has ties with Russia.
Mr Conte approved two meetings Mr Barr held with Mr Vecchione, according to the Corriere.
Mr Barr has reportedly had multiple contacts with officials and spies in Australia, Britain and Italy in a bid to investigate a probe which concluded that Russia tried to swing the 2016 election in US President Donald Trump's favour.
He first travelled to Rome in August to gather information the White House hopes will undermine the probe, Italian media said.
He returned on Friday again to meet Mr Vecchione, the head of the Department of Information for Security (DIS), just ahead of US Secretary of State Mike Pompeo's trip to Italy's capital.
Mr Mueller's probe led to the conviction of several of Trump's top aides for obstruction and lying to investigators.
But ahead of the 2020 election Trump has painted the investigation and its findings as a "deep state" conspiracy, pointing to conservative media reports as evidence and urging the Justice Department to launch counter-investigations.