Thirty-seven-year-old Jeffrey Wiedemann was arrested in Batavia on Friday on charges of being in a public park when children younger than 18 are present.
A background check of his coaching application caught the violation after he had already attended four practices.
Wiedemann pleaded guilty in 2007 to possession of child pornography. He served 30 months probation.
Wiedemann is required to register annually with the police department where he lives. He followed that rule.