Ken Starr, who rose to national fame in the 1990s as the independent counsel appointed to investigate President Bill Clinton, had a question about another embattled president Thursday during a lecture titled “Investigating the President” at UNLV’s William S. Boyd School of Law.

He asked: “President Trump, has he done it? Has he fired Bob Mueller?”

Students and professors packed in the Thomas and Mack Moot Court room didn’t respond. “Things move fast in Washington,” he joked. “You have to keep your finger on the pulse.”

As Starr acknowledged, his lecture Thursday came as aggressive tweets from President Donald Trump in recent days have increased speculation he might order the firing of special counsel Robert Mueller, who is investigating Russia’s interference in the 2016 presidential election.

“What is there to prevent another Saturday Night Massacre? One seems to be brewing on the banks of the Potomac right now,” Starr said. “He might order the firing. He just fired Rex Tillerson. He just fired Gen. McMaster. He’s firing a lot of people. So how do we stop that from happening?”

Starr predicted that firing Mueller would provoke a similar reaction to the Saturday Night Massacre, a pivotal moment in Watergate during which President Richard Nixon ordered the attorney general to fire the special prosecutor investigating his presidential campaign. Any action to fire Mueller, Starr said, could fuel more discussions of impeachment.

“I think that is likely to be viewed as a Saturday Night Massacre that would likely launch a serious conversation about impeachment,” Starr said.

In Nixon’s case, both his attorney general and deputy resigned instead of carrying out the order.

But Starr said he hoped a similar order from Trump would not trigger a resignation from Deputy Attorney General Rod Rosenstein, who began overseeing the Russia investigation after Attorney General Jeff Sessions recused himself. To his knowledge, Starr said Rosenstein had not promised Congress under oath, as Nixon’s deputies had, that they would specifically protect a special prosecutor.

“I’m not saying he wouldn’t resign,” Starr said of Rosenstein, one of the original Whitewater prosecutors. “It might be, shall I say, an elegant exit.”

Ultimately, Nixon’s directive to fire his special prosecutor was executed by his third in command at the Justice Department, Robert Bork, who was later appointed to the federal bench. Bork appointed a second special prosecutor to the case but not before putting forth regulations that required congressional approval before a firing could occur. Those regulations have since lapsed.

“Demand that we bring back the Bork regulations,” Starr told students.

They should supplement the current regulations for the special prosecutor, he said, which were drafted at the end of the Clinton administration by former Attorney General Janet Reno.

When Starr was investigating Clinton, he said he was much less exposed than Mueller. Starr had been appointed independent counsel under a post-Watergate congressional act, so unlike Mueller, he was not an officer of the Department of Justice. That legislation has also expired.

As far as the content of the investigation is concerned, Starr said, “what Bob Mueller and his team know, for us, is a black box.”

But he sharply criticized Russia’s role in American politics, much of which was outlined in Mueller’s recent indictment of 13 Russian nationals.

“The indictment… demonstrates that Vladimir Putin has been operating indirectly through his vast array of oligarchs who feast at the Kremlin table,” Starr said. “And his goal to undermine the democratic ethos.”

Starr, who became a politically divisive figure in the 1990s while investigating Clinton, said that presidential investigations have always sparked partisan rancor.

“My thesis for your consideration is this,” Starr said at the start of his talk. “In light of our unflinching and admirable insistence on honesty and the long history of presidential investigations from Ulysses S. Grant all the way to Donald Trump, we should stipulate to the following simple proposition: There is no perfect way to investigate the president.”

He added: “Someone is going to get very angry.”