In a perplexing exchange during testimony in the House Judiciary Committee, former special counsel Robert Mueller claimed he was "not familiar" with Fusion GPS.

Mueller's testimony thus far has mostly been an effort by Democrats to highlight the more incriminating elements of the special counsel investigation, and get him to verbally refute President Trump's sweeping "total exoneration" claim. Republicans, on the other hand, have been taking it as an opportunity to vent about their frustrations with the Mueller investigation and his report. Mueller has been mostly deflecting questions by referring members to his report.

One odd exchange came when Rep. Steve Chabot. R-Ohio, tried to bring up Fusion GPS, the opposition research firm that was hired by the Hillary Clinton campaign and the Democratic National Committee to dig up dirt on Trump, and ended up hiring British spy Christopher Steele to compile salacious and unverified information on Trump's ties to Russia.

It was expected that Mueller would deflect any questions that get into the early origins of the investigation.

But when Chabot asked him about Fusion GPS, he at first suggested he was not even familiar with the group.

"On page 103 of volume 2 of your report, when discussing the June 2016 Trump Tower meeting, you reference, 'the firm that produced the Steele reporting,'" Chabot said. "The name of that firm was Fusion GPS, is that correct?"

Mueller, looking at a binder with a copy of the report, asked, "And you're on page 103?"

Chabot asked again, "When you talk about the firm that produced the Steele reporting. The name of the firm that produced that was Fusion GPS. Is that correct?"

Mueller responded, "I'm not familiar with that."

How is that even possible? It's one thing to argue that he isn't going to answer questions with reference to Fusion GPS (something he did in follow up questions, with the phrase "it's outside my purview"), but how on earth could he not be familiar with the firm that has played such a key role in the Russia story?