Last Friday, several days after firing FBI Director James Comey, President Donald Trump tweeted something that continues to invite confusion and speculation on Capitol Hill and in the press corps:

James Comey better hope that there are no "tapes" of our conversations before he starts leaking to the press! — Donald J. Trump (@realDonaldTrump) May 12, 2017

Did Trump really tape his conversations with Comey, or was he bluffing? If Trump does have tapes, would they really vindicate him—or would they support the story, reported by The New York Times, that he asked Comey for a loyalty pledge?

We now know that at least one person was keeping records of their conversations: Comey himself.

The Times reported Tuesday that, according to a memo Comey wrote immediately after meeting with Trump in February, the president had asked him to end the federal investigation into Trump’s former national security adviser, Michael Flynn, who had misled the White House about his conversations with the Russian ambassador and made himself vulnerable to Russian blackmail. “I hope you can let this go,” Trump allegedly told Comey. As the Times notes:

The existence of Mr. Trump’s request is the clearest evidence that the president has tried to directly influence the Justice Department and F.B.I. investigation into links between Mr. Trump’s associates and Russia.... The memo was part of a paper trail Mr. Comey created documenting what he perceived as the president’s improper efforts to influence an ongoing investigation. An F.B.I. agent’s contemporaneous notes are widely held up in court as credible evidence of conversations.

Whether or not Comey’s notes end up as evidence in court, they will be of great interest to those who are leading investigations into the Trump campaign’s involvement in Russia’s subversion of the U.S. election—including in the Republican-controlled Congress.