Story highlights President Trump has attacked Comey's credibility publicly

It was previously reported Mueller was looking at obstruction of justice

Washington (CNN) President Donald Trump's legal team has met with special counsel Robert Mueller to discuss the investigation and has prepared memos arguing Trump did not obstruct justice when he fired then-FBI Director James Comey, a source familiar with the memos tells CNN.

The source said the memos prepared for Mueller argue the President's powers under the Constitution inherently give him the right to fire the FBI director for any reason, meaning the move could not have been obstruction of justice.

The President's lawyers have said publicly they would file a complaint against Comey with the Department of Justice. Instead, the source said one of the memos written to Mueller was written as that complaint.

The President's lawyers also called Comey's credibility into question by arguing he was an admitted leaker -- arguments Trump's team has made publicly.

The meeting and details of the memos were first reported by the Wall Street Journal Thursday.

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