[Hog1]

This is sensitive stuff, and if I offend you you, it is not my intention.
My first inclination is (as always) to fight back.....HARD. BUT, in reality, you are getting second hand info, the may not be accurate. The problem is this.
1) Witness's to events have a bad habit of stepping up to back you until you NEED backing. Then, traditionally, they disappear, and did not hear or see anything.
2) He is the buddy of the boss, and the boss is in the position to make your friends life hard and those that might step up to help your friend. Jobs are at a premium at this time.
While it may hurt his pride, it may be better to see if this will die on it's own. Once you lawyer up, things get real complicated...fast.
If charges are filed through Govt. agency of some kind (and they may be justified) your friend may find himself on an island, and ostrasized.
Additionally, if public records exist on this sort of filing, employers are reluctant to hire people that make to many "waves".
CONSEQUENTLY, my advice is catch the bastard "off-site" and kick the golfin' shit out of him!!!!
Have a nice day!