Well press charges against him and tell your friends to not beat him up.
Easy enough IMO.
EDIT: And if that doesn't work (Ie the cops don't belive you) Kick his ass real good. (Make sure not to kill him tho)
Guys I just saw this in the newest TechQuicke video and I couldn't stop laughing.
Look at him! He's got so much Swag!
Also that was on Christmas. (25th December 2005)