If he is out of office, you don't have to/can't impeach him. Because of politics, he is unlikely to face prosecution.
We need to make it INEVITABLE that he faces prosecution.
If he’s going to be charged with treason, it better be done through impeachment though, because if it was done through law enforcement I think it would go to the Supreme Court, and we’ve already got 2 justices who should recuse themselves but won’t.
Perjury and fraud would be good things for him to be prosecuted for...