One week after two 18-year-old women were allegedly drugged and sexually assaulted at an unregistered semiformal event at Beta Theta Pi, the fraternity has voluntarily placed itself on social probation.

"The chapter has shown that they are more than willing to cooperate with the ongoing investigations," Interfraternity Council President Marc Hustvedt said.

The fraternity will not hold any social events indefinitely.

Hustvedt said the fraternity"s actions demonstrate that members want the situation to be resolved quickly.

"I think this was definitely the right thing to do and shows that there is some strong leadership in the chapter," he said.

Beta Theta Pi notified IFC"s Social Responsibility Committee of its decision to go on probation, and the committee decided not to issue further terms of probation until the criminal investigation is complete.

Beta Theta Pi may also go before the Greek Activities Review Panel for potential charges of misconduct.

The Ann Arbor Police Department has identified two male suspects, one in each case.

Joe Burke, Washtenaw County"s chief assistant prosecuting attorney, said the investigation into the sexual assaults, classified as third-degree criminal sexual conduct, is ongoing. Third-degree criminal sexual conduct is a felony charge, punishable up to 15 years in prison.

Police first received a report Friday from a freshman who said she had been raped while attending an unregistered semiformal at the Beta Theta Pi house, 604 S. State St. She also said she believed someone may have put some type of drug in her drink.

Another female freshman went to police with a similar story on Tuesday.

Burke said yesterday that neither of the cases had been turned over to his office, and no charges have been filed against either suspect.

AAPD detectives have not found any evidence that the women ingested any drugs, such as gammahydroxy butyrate or GHB, commonly referred to as the "date-rape drug."

Hustvedt said the recent events have forced many in the Greek community to think about its policies.

"I think this is a real call to action that we as a Greek community need to re-evaluate how we hold our social functions," Hustvedt said.

Locations other than fraternity houses seem to be a more favorable option for Greek events, he said.

"This is ultimately a safer, lower-risk social environment that I think will be the best for our community."