President Trump’s admission that he never taped his conversations with ousted FBI Director James Comey risks exposing him to fresh legal jeopardy and weakens his credibility in the eyes of investigators probing ties between his associates and Russia.

With a tweet Thursday, Trump ended more than a month of suspense about whether he had, in fact, recorded his interactions with the FBI chief he fired on May 9, declaring that “I did not make, and do not have, any such recordings.”

Yet his declaration did little to end the controversy he started with a series of tweets days after Comey’s ouster, suggesting the existence of tapes to keep the former FBI chief from accusing the president of wrongdoing. Lawyers with experience in similar cases say his behavior may be important to special counsel Robert Mueller’s Russia probe, which is now exploring the possibility Trump sought to obstruct justice.

The tweets targeting Comey “could be relevant” to an obstruction investigation, even if the tapes don’t actually exist, said Julie O’Sullivan, a former federal prosecutor who worked on the team investigating Bill and Hillary Clinton during the Whitewater inquiry.

“It’s basically trying to tell Comey, ‘Don’t say anything,’ ” said O’Sullivan, now a law professor at Georgetown University.

.@POTUS on why he wanted former FBI Dir. James Comey to believe there were tapes of their conversations pic.twitter.com/pCuibM5Z6k

— FOX & friends (@foxandfriends) June 23, 2017

Trump has insisted there was no collusion between his campaign and Russian government officials who sought to manipulate the outcome of the 2016 election, and he has scoffed at the suggestion he’s interfered in an investigation he regularly dismisses as a “witch hunt.” But his interactions with Comey have done him no legal favors, lawyers say, raising the prospect that his undoing may be his tampering in an investigation rather than the suspicions that led to the probe.

“With all of the recently reported electronic surveillance, intercepts, unmasking and illegal leaking of information, I have no idea whether there are ‘tapes’ or recordings of my conversations with James Comey,” Trump also said on Thursday.

His suggestion that he was suspicious someone may have been eavesdropping on the conversation is at odds with Comey’s testimony that the president requested others in the Oval Office leave before he asked the FBI director to drop an investigation of Michael Flynn, Trump’s former national security adviser. Trump’s version doesn’t explain why he wouldn’t have wanted Attorney General Jeff Sessions or son-in-law Jared Kushner as witnesses to the conversation.

Investigators will examine what Trump had to gain by implying after he fired Comey that he had a recording of the conversation, said Jim Robenalt, a Cleveland-based lawyer and presidential historian. Robenalt lectures nationally with John Dean, the former White House counsel whose testimony helped bring down President Richard Nixon, and teaches a continuing legal education class on Watergate.

“You’ve got to ask the question: Why is somebody threatening tapes other than to try to intimidate somebody? And then the fact that they said they don’t have tapes, to me, as a lawyer, raises a huge red flag,” Robenalt said. “Did some tapes exist that were harmful that have been destroyed? Why would somebody threaten tapes that don’t exist?”

Rep. Adam Schiff of California, the senior Democrat on the House Intelligence Committee, said the White House must still respond in writing to the panel’s request for any tapes, which carried a June 23 deadline.

“While I would certainly hope that the President’s most recent statement is true, we will continue to pursue the matter with other witnesses so that the public can be assured that if recordings were ever made, they will be preserved and be made available to the committee and ultimately to the public, as well,” he said in a statement.

A core tension in any inquiry will be Comey’s honesty and credibility versus Trump’s. The president’s earlier suggestion that he had tapes that he now says never existed undercuts him, Robenalt said.

Comey, on the other hand, wrote detailed memos immediately after his conversations with Trump and distributed them to associates. He also told trusted people about his concerns soon afterward, well before Trump fired him.

The former FBI director’s memos on the interactions “are going to be very important to any fact-finder. That kind of note-taking is highly credible,” Robenalt said.

Still, Ronald Rotunda, a Chapman University law professor who was assistant majority counsel on the Watergate committee, said there is nothing inherently wrong with Trump using the possibility of tapes as a ruse. It’s entirely plausible that “Trump intimated there might be tapes in order to keep Comey honest,” Rotunda said.

White House spokeswoman Sarah Sanders declined to elaborate on Trump’s tweets in a briefing with reporters afterward. “The president’s statement via Twitter today is extremely clear,” she said. “I don’t have anything to add.”

Trump had faced a Friday deadline to answer a request from Schiff’s panel for information on whether recordings of Comey’s conversations with Trump exist and, if they do, for copies of the tapes.

According to one person familiar with the matter, who spoke on condition of anonymity, Trump raised the possibility of tapes as a strategy to ensure that Comey told the truth, even though Trump now is suggesting that did so because he couldn’t be sure there were no recordings made by others.

“James Comey better hope that there are no ‘tapes’ of our conversations before he starts leaking to the press!” Trump wrote on May 12. He concluded with a tweet calling the investigation into Russian interference in the election and his campaign’s possible involvement a “witch hunt,” asking, “when does it end?”

Comey told a congressional panel that it was Trump’s tweet suggesting the president made recordings of their conversations that spurred him to orchestrate leaks about his memos that documented the encounters.

The day after the description of one memo was published by the New York Times on May 16, Deputy Attorney General Rod Rosenstein appointed Mueller as a special counsel to investigate Russian meddling in the 2016 presidential election, including potential collusion with Trump associates.

Bloomberg’s Billy House Jennifer Epstein and Shannon Pettypiece contributed to this story.