allen was given ten days in segregation. locked down 23 hours a day with no privileges. but it's something he's grown used to. >> you do so many years in the penn, ain't nothing bothers you. >> narrator: allen's willingness to fight over his mustache is one of a seemingly endless supply of reasons others resort to violence. another fight is just broken up between three inmates in one of the general population housing units. >> the sert subdues the fighters and starts the investigation. the aggressors appear to be guadalupe. neither man shows any sign of injury. victor sanchez will require medical attention. >> his obvious injuries are a black eye and a cut on the back of his head. sergeant tucker now takes over from sert in finding out what happened. >> i saw you swinging at him. you both had him cornered. you want to stand there and lie to me some more? >> right, there was a lock down for nothing. what did you hit him with? >> my hand. >> who had the thing that cut the back of his head open? >> oh, i don't know about that. >> right. >> as tucker interrogates, sanchez undergoes his medical evaluation where an entirely new injury is discovered.