President Donald Trump maintained his position that former President Biden was not aware "what was going on" when he served as president as Biden brushed off the autopen probe.

Presidential use of the autopen is not illegal. And Trump admitted that his staff uses the device to mimic his signature on letters.

President Trump has directed a wide-ranging investigation into former President Biden, accusing his aides of using “autopen” signatures to cover up his “cognitive decline.” NBC News’ Peter Alexander explains what we know — and the lack of evidence Trump has presented.