The Nov. 2 report, released Wednesday by Bixby High School, said the Tulsa-area school's investigation began Oct. 26. It included interviews with the boy and his mother, who told officials that a teammate had inserted a pool cue into his anus through his shorts.
An affidavit filed last month by investigators provided a fuller account of the assault, which took place in September during a team function at the superintendent's house. The football player told detectives he was assaulted by one player while three others held him down. Investigators say a fifth player recorded the assault on a cellphone, and another blocked a door, according to the affidavit.
The boy also told investigators in the earlier affidavit that he had been assaulted in a similar manner during a team function at the superintendent's house in 2016. The Nov. 2 report by the school references "two separate occasions" in which "a hazing incident resulted."
Authorities have seized the cellphones of several administrators and football players and ordered emails from the superintendent, principal, athletic director and football coach. They said last month that the delay by school officials in reporting the assault may have jeopardized investigators' ability to recover key evidence.
A search warrant said some school officials may have tried to "not report the incident at all" - which is a misdemeanor offense under Oklahoma law.
School officials and local police have declined to comment and referred questions to the Oklahoma State Bureau of Investigation, which is leading the investigation.
Agency spokeswoman Jessica Brown said Thursday that investigators are still conducting interviews and collecting evidence.
A recent investigation into a similar sexual assault case at a prominent high school in Arizona has seen police recommend charges against the principal, athletic director and head coach. Authorities accuse them of knowing about allegations of abuse involving the football team but failed to alert authorities.
An Associated Press investigation published earlier this year examined sexual violence in school sports as part of a larger look at student-on-student sex assaults. Teammate-on-teammate sexual assaults occurred in all types of sports in public schools, and experts said the more than 70 cases in five years that AP identified were an undercount.
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