Senate Judiciary Committee asks for copies of leaked memos The committee requested the memos from Daniel Richman on Thursday.

 -- The Senate Judiciary Committee has formally requested copies of former FBI Director James Comey's memos from his friend Daniel Richman, a Columbia University Law School professor, ABC News has learned.

The committee sent a bipartisan letter to Richman on Thursday, signed by Sens. Chuck Grassley, Dianne Feinstein, Lindsey Graham and Sheldon Whitehouse, as part of the panel's ongoing Russia investigation. Richman declined to comment in an email to ABC News.

Comey testified Thursday before the Senate Intelligence Committee that he no longer has copies of his notes and had turned them over to special counsel Robert Mueller. Four congressional committees have appealed directly to Comey and the Department of Justice to obtain the memos for review but have not yet obtained them.

Comey said he asked Richman to share his notes with the press after Trump tweeted about "tapes" of their White House conversations.

"I asked a friend of mine to share the content of the memo with a reporter. Didn't do it myself for a variety of reasons. I asked him to because I thought that might prompt the appointment of a special counsel. I asked a close friend to do it," Comey told Senate Intelligence Committee members.

The Senate Judiciary Committee has been working to obtain the memos and any possible White House recordings of Comey's interactions with President Trump. It has oversight jurisdiction over the Department of Justice.

Chairman Chuck Grassley, R-Iowa, wants Comey to appear before his committee, and has not ruled out issuing a subpoena for his appearance.

Following Comey's Thursday appearance, congressional investigators say they plan to focus on his FBI associates and others who may have been privy to his conversations with Trump.

"We need to talk to those people around Comey that he shared his experiences with at the time they were happening and indeed as he said today, some of those folks were in the room while the president was on the other line," Rep. Adam Schiff, D-Calif., told ABC News in an interview Thursday.