The U.S. Center for SafeSport has banned swim coach Sean Hutchison from participating in any activity or competition organized by the United States Olympic Committee after an investigation into sexual abuse allegations from an Olympic athlete.

Olympian Ariana Kukors from Auburn, Wash. said earlier this year that Hutchison started child “grooming” her when she was 13 years old after he became her coach at a Federal Way swim club. Kukors says Hutchison started sexually abusing her three years later.

Internal investigation documents obtained by KING 5 from the U.S. Center for SafeSport show the organization found “a preponderance” of evidence that Hutchison engaged in sexual misconduct with Kukors that violated SafeSport code, Washington and California state law, and expectations of USA Swimming members, which prohibits “inappropriate sexually oriented behavior or action directed towards an athlete by a coach.”

The U.S. Center for SafeSport is a national organization that aims to end abuse in sport. The non-profit says it has been entrusted by the U.S. Olympic Committee to respond to reports of sexual misconduct in U.S. Olympic Movements.

The investigation found that the 18-year age difference between Hutchison and Kukors and direct athlete/coach relationship were aggravating factors, “reflecting an extreme imbalance of power.”

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Hutchison declined an interview or statement with SafeSport as part of their investigation. Kukors also declined an interview but provided a signed affidavit.

Hutchison has denied the inappropriate relationship, saying he did nothing to groom her or do anything that was not consensual.

Kukors and her attorney declined to comment on the investigation.