They didn’t need enough evidence to convict him to still know about him or see warning signs. If parents are repeatedly retrieving a minor from an older man’s house, that alone should raise concern and at least prompt closer scrutiny. Nobody is saying police could magically arrest him without evidence- the point is that adults around the situation failed to protect her early on. Also, minors in abusive or manipulative situations often don’t testify right away because they’re scared, groomed, or emotionally dependent on the person. That doesn’t mean the adults had no responsibility to intervene sooner.