A former MI6 officer who produced the dossier alleging that Russian intelligence has compromising information that could be used to blackmail Donald Trump has gone into hiding after being unmasked in media reports.
Christopher Steele, 52, reportedly fled his gated home in Surrey after the report was published in full by news website Buzzfeed, only hours before his identity was revealed.
Steele, who is the director of London-based Orbis Business Intelligence Ltd, produced the report which contained allegations from Russian sources that the Kremlin had footage of Trump with prostitutes in Moscow, and that members of the Trump camp had secretly colluded with Russia.
The report was initially funded by Republican opponents of Trump, and subsequently by the campaign of Democrat Hillary Clinton.
The report sparked furious condemnation from Trump, who accused intelligence services of leaking the report, and attacked CNN and Buzzfeed for spreading "fake news" for reporting it.
Steele, who reportedly worked as a spy in Moscow in the 1990s, left his home in the early hours and left his cat with a neighbour, saying he would be away "for a few days", The Telegraph reported.
A diplomatic service list shows he was posted to the UK embassy in Moscow in 1990 with the title of 'second secretary', serving under ambassador Sir Rodric Braithwaite.
A source told The Times that Steele could have been involved with Russia issues for British intelligence for almost two decades, and was "in place" when former KGB spy Alexander Litvinenko was killed in London in 2006. A public inquiry found the murder was carried out by Russian intelligence operatives, probably on the orders of Russian president Vladimir Putin.
"I think he [Mr Steele] was one of the people who was working with Litvinenko," said the source.
The BBC was told by members of the intelligence community that Mr Steele was "extremely, highly regarded" and was thought of as "competent".
After leaving MI6, Mr Steele founded Orbis Business Intelligence Ltd with his business partner Christopher Burrows, 58, who used to work for the Foreign Office, in 2009. The business says on its website it was formed in 2009 by former British intelligence professionals.
The firm relies on a "global network" of experts and business leaders to provide clients with strategic advice, mount "intelligence-gathering operations" and conduct "complex, often cross-border investigations," its website says.
Burrows would not confirm or deny that Steele was the author of the report, when contacted by The Wall Street Journal.