The timing of President Donald Trump’s dinner with FBI Director James Comey raises the question of whether the president attempted to—or did in fact—interfere with an ongoing FBI investigation. And that’s a federal offense.

The episode in question occurred in the earliest days of the Trump administration. Within days of Trump’s start at the White House, the Justice Department had reason to believe that National Security Adviser Michael Flynn may have been compromised by the Russians. Flynn was interviewed by the FBI on January 24.

On January 26, Acting Attorney General Sally Yates rushed to the White House to tell Trump’s top lawyer of the Justice Department’s suspicions. She returned, at the White House counsel’s request, to continue the discussion on January 27.

That same night, the evening of January 27, the president had dinner with Comey, according to James Clapper, the former director of national intelligence, who told this to NBC News.

Peter Zeidenberg, a former federal prosecutor who convicted Scooter Libby for leaking a CIA agent’s name, told The Daily Beast that the context of Trump’s dinner is “really significant.”

“So even if he’s not obstructing an investigation into himself, he may be obstructing an investigation into Flynn,” said Zeidenberg, a former assistant U.S. attorney for the District of Columbia.

“Asking him for his loyalty, I don’t know if that would qualify as obstruction of justice in and of itself,” Zeidenberg said, adding, “That suggests consciousness of guilt.”

At the time that the president had dinner with the FBI director, it appears that he was aware of the FBI’s interest in Flynn. Press Secretary Sean Spicer told reporters in February, “Immediately after the Department of Justice notified the White House Counsel of the situation, the White House Counsel briefed the President and a small group of senior advisors.”

In the context of these warnings from the Justice Department about Flynn, Trump reportedly asked Comey at this dinner if he would be loyal to him. According to The New York Times, Comey pledged that he would always be honest, but not politically “reliable.”

Trump told NBC News that he asked Comey during the dinner if he was under investigation, and claimed the answer was no. Two people who heard Comey’s account told the New York Times he did not answer Trump’s question.

Despite Flynn being caught in a lie—and becoming a potential blackmail target of Russia—the White House did not fire him for 18 days, until shortly after the Washington Post reported Yates’ warning to the White House.

Trump’s firing of Comey may also constitute obstruction of justice, according to Zeidenberg.

“I think it’s much more likely that he admitted yesterday to Lester Holt that the Russia investigation was top of mind [when he fired Comey] creates a real problem, for obstruction of justice. That to me is way more troubling.”

Trump tweeted the day before he fired Comey: “The Russia-Trump collusion story is a total hoax, when will this taxpayer funded charade end?”

“That is really close to the line if not over it. He’s aware of an ongoing investigation and he’s obviously concerned about it, according to Trump, asking Comey three times if he was under investigation,” Zeidenberg said.

Bradley Moss, a national security attorney, said things are looking worse for the president.

“The pieces are coming together but they are not there yet,” Moss told The Daily Beast. “There is certainly circumstantial evidence there is a link” between Trump’s dinner and his briefing from McGahn that Flynn was being investigated.

“The president having the meeting with the specific intent to obstruct and interfere with what might actually become a legal proceeding” would have to be proved, Moss said.

As for Trump’s firing of Comey, Moss said the reason doesn’t matter from a legal standpoint.

“Not only would he have to fire Comey, but also take some affirmative step that whoever replaces Comey does not target this particular target of the investigation,” Moss said.

The president has “unfettered discretion” to fire Justice Department officials like Comey.

“I don’t see Comey’s firing in and of itself being something that could serve as the basis for articles of impeachment,” Moss told The Daily Beast. For instance, Richard Nixon’s firing of attorneys general and a special prosecutor ultimately was not included in articles of impeachment drafted by the House.

Zeidenberg said, again, it’s comes down to context.

“You argue inferences” as a prosecutor, he said. “The fact that he doesn’t say ‘I’m trying to stop the investigation’ doesn’t mean you don’t have a potential case. He’s gone pretty far the way down the road.

“A prosecutor doesn’t usually get a defendant to explain and admit the reasons for his conduct.”

Whatever the reason, Zeidenberg said Trump is panicking.

“He seems extremely fearful of what that investigation is going to uncover. If it truly was a nothingburger, there’s nothing here, why not open the kimono?”

Zeidenberg said Trump could sit down for interviews, tell his staff to be interviewed, and say, “I want this all cleared up, as soon as possible.

“Instead it’s just the opposite. It’s not the conduct one would expect from someone who doesn’t have anything to hide,” he said.

Not content with firing Comey, the president threatened him on Friday.

“James Comey better hope that there are no ‘tapes’ of our conversations before he starts leaking to the press!”

Because Comey can be called as a witness in future congressional hearings (the Senate Intelligence Committee has asked him to speak next week) or asked to testify before a grand jury means Trump’s tweet could be considered witness tampering, legal experts said.

“The short version is that it comes awfully close to the letter of the federal witness tampering statute,” University of Texas law professor Steve Vladeck told The Daily Beast.

The relevant statute cites witnesses in official proceedings, not just criminal ones.

“Congressional hearings are certainly official proceedings under the witness intimidating statues,” Vladeck said. “Forget Comey ever testifying before a grand jury or a criminal case. The federal witness tampering statute would apply to a federal oversight hearing the same way it applies to a criminal prosecution.”

Trump’s defense might be that he was only trying to “encourage Comey to be truthful,” Vladeck said, but a reasonable person would think that “Trump is trying to cow Comey into silence.”

Without more evidence and with Republicans in control of Congress, there’s almost no risk Trump is facing prosecution anyway, according to Vladeck.

“That the reaction to this churlish and childish behavior to the president should be the opposite he intends,” Vladeck said.

“Every time President Trump reaches for Twitter, the folks involved in investigating him should reach for some coffee and the rest should reach for something stronger,” he added.

The most important and immediate questions are about who will lead the Russia investigation.

“The real story now shifts to what Ron Rosenstein does next and who Trump nominates to succeed Comey,” Vladeck said.

The pressure will be on the Senate Judiciary Committee to vet Trump’s nominee to lead the FBI—and the pressure will be most acute on the committee’s three Republicans up for reelection in 2018.

If Trump nominates a loyalist, “Are they going to stand up to or say no?” Vladeck asked.

—with additional reporting by Tim Mak