As always, Republicans accuse and then investigate. Republican openly commit crimes, Republicans investigate the crirmes committed, and then AG's prosecute the crimes found, based on the evidence produced by the investigation.
Donald Trump was prosecuted on the basis of his life long criminal record, all of which was upheld by grand juries; trials in front of juries where both sides presented their evidence; and Trump was found guilty - in 4 different jurisdictions, in multiple states.
Nobody could have prosecuted Trump if he hadn't publically committed these crimes in the first place. The whole world has watched his unchecked corruption, lies, and scams. His claiming that nothing he did was illegal is just another lie. If it wasn't illegal, he wouldn't have gone to such lengths to cover it up.
And still you say Trump's not a criminal, and the Democrats who have never been charged are "above the law". Maybe if Republicans waited until a Democrat commits a crime instead of making shit up and then trying to prove it really happened, you'd have better success.