mad men star was charged with assault for november 1990 hazing incident .
allegedly viciously beat pledge for the sigma nu fraternity at ut-austin .
hamm and other frat brothers put pledge through humiliating initiation .
allegedly struck him with a paddle 30-times and set fire to his pants .
the alleged victim 's mother called the police and arrest warrants issued .
hamm had a summons issued to him after he left ut-austin in 1992 .
the incident led to the permanent closure of the sigma nu fraternity .