Pictures of two people engaging in sexual relations in broad daylight on the roof of Waite Phillips Hall of Education were posted online Saturday.
USC security workers said the two triggered an alarm by opening the roof door and that other students called in to report the incident.
The Daily Trojan reports the man in the pictures is a student and member of the fraternity Kappa Sigma. He has been suspended from his fraternity until an investigation is completed.
That fraternity issued a written statement this week that reads in part, "The member in question has been suspended from Kappa Sigma for conduct unbecoming of a Kappa Sigma and a gentleman until a more detailed investigation can be conducted."
The woman is a student at a different local university.
USC school administrators did not immediately return calls seeking comment.
Some students, however, say the student shouldn't be punished.
"It's just a prank," said Eric Dilan. "I find it pretty funny."
Leaders of the councils that oversee USC fraternities and sororities plan to meet Tuesday night to decide if further action should be taken.