The former British spy behind a controversial dossier about Donald Trump’s Russian links has spent two days talking to US investigators, it was reported on Wednesday.
Christopher Steele met behind closed doors with colleagues of Robert Mueller, the special counsel looking into Russian election meddling, according to The Washington Post.
It means that investigators will be able to judge firsthand whether they think claims reported by Mr Steele in the dossier are trustworthy.
Mr Steele has previously refused requests to appear before Congressional committees looking into how Russia interfered in the 2016 election.
The Washington Post also reported that Mr Steele compared possessing the information he found about Mr Trump to “sitting on a nuclear weapon”.
The paper's 4,000-word article provides the fullest picture yet of how Mr Steele acted after uncovering claims that the Russians had compromising material on Mr Trump.
Mr Steele and his “dossier”, a series of memos written after funding from first Republican then Democrat opponents of Mr Trump, lies at the heart of the Russian election meddling row.
Among the claims made was that Mr Trump asked prostitutes to conduct lurid sex acts while in Russia. Mr Trump has vehemently denied the allegations.
The dossier, published after the election by Buzzfeed, has become the focus of a fiercely partisan battle over the Russian investigation, which is looking into links with the Trump campaign team.
Republicans have sought to portray Mr Steele as politically motivated and his claims as unfounded, indicating the entire Russian investigation is constructed on his faulty intelligence.
However Democrats have painted Mr Steele as someone who passed on concerns in good faith and stressed his information was not the only reason for starting the Russia investigation.
Profile | Christopher Steele
The Washington Post described how Mr Steele, a Russian expert so trusted that he had provided briefings for UK prime ministers and at least one US president, got drawn into the Trump case.
It describes how after Mr Steele's consulting firm Orbis Business Intelligence was commissioned to look into Mr Trump he became increasingly concerned by the discoveries, coming from his network of informants.
Mr Steele eventually reached out to the FBI, who he had worked with exposing Fifa corruption, so he could brief them on what he found.
He met with the Washington Post twice before the election in an attempt to get them to cover the claims, the second time appearing “visibly agitated".
The Washington Post, however, declined to publish as they were unable to verify the claims in Mr Steel's report.
Mr Steele also reached out to old intelligence colleagues for advice, apparently convinced the information he had found was significant to national security.
Richard Dearlove, the former head of MI6, met Mr Steele and his colleague at London's Garrick Club, where Mr Steele reportedly expressed his worries.
Sir Andrew Wood, a British former diplomat and friend of Mr Steele, was also asked for his thoughts. “He wanted to share the burden a bit,” Mr Wood told The Washington Post.
After Mr Trump won the election, an ally of John McCain, the Republican senator, visited Britain to meet Mr Steele and read the dossier for himself.
He was reportedly told to "look for a man wearing a blue raincoat and carrying a Financial Times under his arm” at Heathrow Airport. A copy of the dossier was eventually passed to Mr McCain.