(CNN) In a press gaggle Friday morning, President Donald Trump refuted the claim that he ever told former White House counsel Don McGahn to fire Robert Mueller. "I'm a student of history. I see what you get when you fire people and it's not good," Trump told the press, repeating his claim, "I never told Don McGahn to fire Mueller."

The Facts First team investigated this assertion when Trump tweeted it Thursday morning. Here's what we found

Facts first: The Mueller report finds that "substantial evidence" supports the conclusion that Trump directed McGahn to call Deputy Attorney General Rod Rosenstein to "have the Special Counsel removed." The report then details how Trump attempted to cover up the episode.

From multiple interviews with McGahn and others, the report states that after news broke saying Trump had ordered McGahn to fire Mueller, "the President ... sought to have McGahn deny that he had been directed to remove the Special Counsel." McGahn rejected this command and "insisted his memory of the President's direction to remove the Special Counsel was accurate," the report states.

Later, in a conversation with McGahn, Trump asked, "Did I say the word 'fire'?" McGahn replied, "What you said is, 'Call Rod (Rosenstein), tell Rod that Mueller has conflicts and can't be the Special Counsel." Trump replied that he never said "fire" and merely wanted McGahn to bring Rosenstein's attention to the perceived issue and leave it to him, according to the report.

Read More