The House Judiciary Committee, under Democrat Jerry Nadler, then launched an impeachment investigation against Trump. But that stalled when key witnesses, most prominently McGahn, refused or were denied White House permission to testify.
Fromer White House counsel to president Donald Trump, Donald McGahn has finally agreed to testify to a House committee on allegations that Trump obstructed justice during the 2017-2019 Mueller investigation.
When media heard of that, Trump also allegedly ordered McGahn to deny it ever happened . Mueller's March 2019 final report also cited McGahn's testimony on other allegations of obstruction by Trump.
A transcript of the interview will be made public. But even if McGahn supports the allegations of obstruction, it is not clear how the committee will proceed against Trump, who was impeached an unprecedented two times for actions separate from what Mueller investigated.