Frank LoMonte, executive director of the Student Press Law Center, said the school held student conduct hearings against the FarmHouse fraternity and former fraternity member Nathan Michael Cochran, 22.
Cochran was accused of sexual assaults, but school officials did not notify police, LoMonte said.
OSU officials learned of the incidents Nov. 12, when several male students claimed they had been sexually assaulted. The school began hearings, which concluded Nov. 30 with the suspension of Cochran, the (Oklahoma City) Oklahoman reported Monday.
Police opened an investigation into the matter Dec. 7, nearly a month after the initial report, when a reporter from the campus newspaper contacted police with questions about the alleged assaults, said Stillwater, Okla., police Capt. Randy Dickerson.
School officials have maintained requirements of the federal Family Educational Rights and Privacy Act, or FERPA, prevented them from turning information about the allegations to police, the newspaper said.
"The reliance on that (explanation) is so frivolous that it really calls into question whether they could possibly believe that themselves," LoMonte said.
Capt. Dickerson said Thursday he was "stunned" by the school's explanation for not notifying police, in particular by its contention Cochran no longer posed a threat after his suspension from the university, and that, after five students reported an assault, university officials should have involved the police.
"I would certainly draw the conclusion that one suspect who had sexually assaulted five young men might be considered a threat to other students," Dickerson said.
Thursday OSU President Burns Hargis asked Board of Regents chairman Andy Lester to review the school's handling of the situation, the newspaper said.