Columbia professor Daniel Richman appears to have gone into hiding after it emerged that he had leaked James Comey's memo on his meeting with Donald Trump.

Comey testified on Thursday that he had asked a friend at Columbia to release the memo, in which he wrote that Trump had asked him to squash the investigation into Mike Flynn's Russian ties.

Richman, the Paul J Kellner Professor of Law at Columbia Law School, confirmed after the hearing that he was the friend in question - and then vanished, the New York Post reported.

James Comey testified on Wednesday that a professor friend from Columbia university leaked his Trump memo. Daniel Richman (right) said he was that friend, and then seemingly vanished

When asked, Comey said the man he asked to leak the memo to the New York Times in May was 'a good friend of mine who's a professor at Columbia Law School.'

Richman confirmed to Mic that he was the professor in question, but then fled his home on Henry Street in Brooklyn's Richmond Heights.

Neighbors refused to answer questions when the New York Post arrived, and a doorman eventually barred their reporter.

Richman is described on the Columbia website as 'a former federal prosecutor who served as chief appellate attorney in the US Attorney's Office for the Southern District of New York.'

It also says that he served as a consultant to the Department of Justice and the Department of the Treasury on federal criminal matters.

Perhaps more pertinently, it says 'He is currently an adviser to FBI Director James B Comey.'

He and Comey worked together when Richman was a federal prosecutor in Manhattan; they also worked together at Columbia in 2013.

Last month the New Yorker called Richman Comey's 'close friend' and 'unofficial media surrogate'.

Richman could not be found at his Brooklyn apartment (pictured) on Wednesday. He and Comey have been pals for years, and he is officially an adviser to Comey

Comey testified that he was spurred into asking Richman to leak the memo after Trump fired him and tweeted that he'd 'better hope there's not tapes.'

He said he woke up in the middle of the night and realized that he could corroborate the conversation through the memo, which he'd written after the meeting.

'And my judgement was, I needed to get that out into the public square,' he said. 'And so I asked a friend of mine to share the content of that memo with a reporter.

'Didn't do it myself for a variety of reasons, but I asked him to because I thought that might prompt the appointment of a special counsel.'