A bipartisan group of powerful senators is asking the man believed to have helped ex-FBI Director James Comey leak his infamous “let this go” memo to the media to produce that memo for them.

Senators Chuck Grassley (R-IA), Diane Feinstein (D-CA), Lindsey Graham (R-SC), and Sheldon Whitehouse (D-DE) — the chairs and ranking Democrats of the Senate Judiciary Committee and its National Security Subcommittee — sent a letter Thursday to Columbia Law Professor Daniel Richman demanding he provide them with the original memo he supposedly leaked to CNN on Comey’s say-so.

The letter calls the memo, reported to describe President Donald Trump telling Comey to go easy on former National Security Advisor Michael Flynn, “relevant to the Judiciary Committee’s ongoing investigative efforts.”

The letter also demanded all other memoranda Comey may have provided Richman and gave him only until midnight Friday. Breitbart News cannot confirm if Richman complied with the senators’ demands.

Richman confirmed to multiple news outlets Thursday that he was the “friend” whom Comey enlisted to leak the memo to the press. This ended speculation that began immediately after Comey admitted under oath he had leaked the memo containing his account of conversations between himself and President Donald Trump. Comey claimed that his hope in doing so, immediately after he was fired, was to force the appointment of a special counsel, which has now come to pass in the person of Comey’s predecessor as head of the FBI, Robert Mueller.

Richman reportedly went into hiding after his name hit the national news and has not been seen in his Brooklyn neighborhood since. His disappearance from view as the request for the memo pends has raised questions about the memo, the validity of which Comey swore by in his Thursday testimony before the Senate Judiciary Committee.

Sharyl Attkisson, reporter for Full Measure News, tweeted her skepticism in light of these developments, including Comey’s own testimony that he no longer has an original copy himself: