We all know the issue with child molesters and yes they shouldn't be near kids. But I think you should leave the guy alone. If he is sincerely trying to move away from his dark past, getting him fired wouldn't help. It could trigger him to moleste another child. The urge to a molester must be some kind of high and escape. Harassment, or complaints won't assist the situation.

Just don't bring your child anywhere near him.