SPOILER ALERT.. DON'T READ IF YOUR NOT DONE WITH THE THIRD SEASON!

The rapist was Mercer Hayes, Logan's buddy who ran the Casino. Though, Wallace & Piz's dorm advisor Mo was helping Mercer by drugging the girls and them taking them back to their rooms. They both got send to prison after Veronica busted them. :)

The rapist at Hearst College was Mercer Hayes. After he raped the girls he would then shave their hair!