Ok, let me preface with saying I am not in your shoes and therefore I don't pretend to know all the details and please don't take this as judging.
But outside looking in and trying to leave emotion out of this, these are the points I thought needed to be in black and white.
#1-You have a known felon with a violent history
#2-You have actual proof of the same known violent felon dealing in guns,
#3-On top of dealing in guns, he is fraudently doing so. (you mentioned misrepresentation)
At what point does letting him walk pass the gut check? Where does civic responsibility come into play? How is this guy different from a sex offender who hurts kids? We would all line up to help get him off the streets, right?
We are all currently fighting crazy politicians to keep our gun rights because guys like this are going around the laws. The politicians are basically saying the gun laws that are in place aren't working, so we need more.
As responsible gun owners I hope we all would do our part in protecting the 2nd admendment by keeping firearms out of the hands of felons, especially violent ones...