In a moment that quickly made the rounds on conservative media on Wednesday, Rep. Jim Jordan sharply questioned Robert Mueller on the origins of the counterintelligence investigation into the Trump campaign’s ties to Russia.

The Ohio Republican pressed the former special counsel to detail who told George Papadopoulos, a young foreign policy aide on the Trump campaign, that the Russians had “dirt” on Hillary Clinton. When Mueller said he would not go into it, Jordan became heated.

“Yes you can, because you wrote about it – you gave us the answer!” Jordan said. “Joseph Mifsud.”

The name of the shadowy Maltese academic kept coming up on Wednesday as Republicans accused Mueller of covering up how the FBI came to investigate the Trump campaign’s alleged ties to Russia, a popular talking point for Trump allies. At the House Intelligence Committee hearing, Rep. Devin Nunes pointed to a large photo of Mifsud with then-U.K. foreign secretary Boris Johnson as evidence that he “has extensive contacts with Western governments and the FBI”.

Mifsud’s name would have been familiar for regular consumers of Fox News and conservative outlets that have spent two years dissecting what they believe was a “deep state” attempt to take down the Trump campaign. The London-based professor at the center of the Trump-Russia probe has not been seen in public since October 2017, just days after Papadopoulos pleaded guilty to lying to the FBI about his interactions with him. One of those was a key conversation in London in April 2016, in which Mifsud told him the Russians had damaging information on Clinton in the form of “thousands of emails.” Mifsud also introduced him to a Russian graduate student that Papadopoulos believed to be Putin’s niece, and connected him with an official with ties to the Russian foreign ministry who said he could set up a meeting with the country’s ambassador, according to Mueller’s report. Papadopoulos later relayed that information to an Australian diplomat, Alexander Downer, who passed it on to U.S. government officials, setting into motion the FBI investigation into Russian contacts with the Trump campaign.

Papadopoulos’ interactions with Mifsud, and his allegation that the Maltese professor was an FBI plant, has been at the center of some Republicans’ efforts to discredit Mueller’s probe. Papadopoulos told TIME in May that he believes he was part of an elaborate set-up by U.S. intelligence to sabotage Trump’s presidential campaign. Since serving a short sentence for lying to the FBI, Papadopoulos has continued to make the rounds alleging that Mifsud was a “Western intelligence operative” who tried to use him to entrap the Trump campaign.

“People are very fascinated about what I have to say, people are just like — their mouths are dropping,” he told TIME on April 17. “They’ve never heard this information because Mueller and the FBI wanted to keep me silenced.”

Perhaps anticipating this line of questioning, Mueller made it clear in his opening statement that he would be “unable to address questions about the opening of the FBI’s Russia investigation” because it is the subject of an ongoing review by the Justice Department.

That did not stop Jordan and Nunes, both vocal Trump supporters, from trying.

“He’s the guy who starts it all, and when the FBI interviews him, he lies three times and yet you don’t charge him with a crime,” Jordan exclaimed, angrily listing others charged by Mueller, including Michael Flynn and “13 Russians no one’s ever heard of.”

“But the guy who puts the country through this whole saga, starts it off, for three years we have lived this now, he lies and you guys don’t charge him,” he said.

“I’m not sure I agree with your characterization,” Mueller tersely responded, but Jordan’s performance was already going viral in conservative corners of the internet with headlines like “WATCH: Jim Jordan Steals the Show, Calls into Question Entire Basis of Probe!” and “‘BRUTAL’: Jim Jordan grills Mueller about why ‘guy who put this whole story in motion’ lied but wasn’t held accountable.” On Wednesday afternoon, Trump himself retweeted a clip of the exchange, indicating that Mifsud is unlikely to fade from the debate over the Russia investigation.

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