Who Alerts the Government

The Washington Post reports here of an investigation of Rep. Alan B. Mollohan (D. W.Va.) . Mollohan has increased his wealth while in office and the question will be whether this increase involved unethical or criminal activity. The repercussions of this investigation have already been felt by him, although investigations can often be very trying on those being examined by the government, irrespective of the position of power that they may hold.   

Like Tom DeLay, Mollohan is calling his investigation "partisan,"  noting the source of the initial information given to the government.

Should it make a difference what the source of the investigation is?  Or should the bottom line be, did the individual violate the law or not?

(esp)