Reply #103: ...what kind of fifty-cent legal bullshit is that? Please, explain to me exactly how

[Occam Bandage]

Congress might have "proof" of any sort of criminal action without a criminal trial. Keep in mind that any declaration of criminal action without a trial would amount to a bill of attainder and would be unconstitutional.

No, Congress is not under any circumstances bound to impeach. The House may impeach if they believe crimes have been committed; there is then a trial in the Senate, which convicts if it believes crimes have been committed and acquits if it believes that has not been proven.