An 18-year-old woman told police she was sexually assaulted during an unregistered party at the Beta Theta Pi fraternity house Friday morning.

Ann Arbor Police Sgt. Paul Curtis said last night that he could not confirm whether the suspect, described as a black male between the ages of 18 and 20, was taken into custody.

Curtis said the woman took herself to University Hospitals after the incident, which she said occurred sometime before 2 a.m. Friday inside the house at 604 S. State.

"She believed that somebody put something in her drink," he said. "She then went into the suspect"s room, where she passed out, and later woke up with no clothes on."

It was unclear whether the victim is a University student or if the suspect is a member of Beta Theta Pi.

Interfraternity Council President Mark Hustvedt said he could not comment on the alleged sexual assault because it is a criminal investigation.

However, he said the party was a violation of IFC policy because the fraternity did not register the event so it could be monitored by members of the Social Responsibility Committee.

Hustvedt said the incident is being looked into by IFC, members of the local Beta Theta Pi chapter and the fraternity"s national organization.

"The chapter is treating this as a very serious issue," he said.

Beta Theta Pi is not an alcohol-free house, Hustvedt said.

However, according to the Greek system"s Social Environmental Management Policy, "any chapter that is found having an unauthorized event is subject to an immediate social probation, the length of which will be determined by the SRC Executive Board."

IFC requires fraternities to register any chapter-sponsored event where alcohol is present, and fraternities must allow monitors to enter parties to ensure that guidelines are being met.