I think this was pure road rage on the part of the Marshall. The kid didn't know he was a Marshall, and according to several eye witnesses, was just trying to leave.
If this Marshall had a legitimate problem with the kid, he could have recorded to license number and followed though that way.
May he get a long stretch in the State pen to think about it.
I often wonder what it is about today's society, beyond the obvious macro-issue of moral decay, that spawns such incredible anger in traffic situations. In years past, you got mad, maybe somebody flipped somebody off, did some screaming, but this kind of vitriolic rage was unheard of. Now it's not uncommon to hear of traffic incidents that turn violent, though thankfully it is uncommon for someone to wind up dead. Very sad.
MM