He used the DOJ to interfere in the trial of a convicted friend.
TOTALLY disproven, because Bill Barr said in an interview with ABC news that Trump "has never asked me to do anything in a criminal case", and he then criticized Trump's tweets. Might as well say, "Look, Don, can't we do the crimes more quietly?".
The interview was probably an exercise in Barr gauging how much credibility and play he still has left in the various media outlets. Because, baybeh, Barr's gonna go on an "election investigations" media tour this summer and fall, in all likelihood. "The DOJ is currently investigating rumors that Senator Sanders possesses a micropenis. We wish him well at the polls tomorrow." But it'll somehow be worse than that.