As far as Congressmen go, they cannot be "fired". They have to be voted by a supermajority (2/3) of the chamber. As much as it should be possible to put them on leave or outright fire them for criminal acts, it isn't, and probably never be, the case. Too much corruption to ever happen. There would need to be a Constitutional Convention and a new amendment needs to be added in for that. That and a lot of other things.