Robert Mueller said he was 'not familiar' with Fusion GPS. How is that possible?

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.