Washington (CNN) President Donald Trump told special counsel Robert Mueller in writing that Roger Stone did not tell him about WikiLeaks, nor was he told about the 2016 Trump Tower meeting between his son, campaign officials and a Russian lawyer promising dirt on Hillary Clinton, according to two sources familiar with the matter.

One source described the President's answers without providing any direct quotes and said the President made clear he was answering to the best of his recollection.

This is the first insight into how the President responded to the Mueller team's written questions -- a key unknown as Mueller aims to wrap up his investigation and prepare his final report.

These two points -- WikiLeaks and the Trump Tower meeting -- are critical to Mueller's central mission: investigating whether the Trump campaign colluded with Russians during the 2016 campaign.

The President's lawyers previously told CNN the answers would match his public statements. Still, these written answers could be subject to criminal charges if false.

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