I honestly don't think anyone here is simple minded enough to imply guilt in this case just because the man looks 'creepy'. This last was merely an aside - a personal observation not meant to reflect on the actual facts of the case.
On the other hand, I totally agree with the professor's actions. We who are parents and teachers are given a special trust to guard the safety of children - our own and other people's. As a former classroom asssistant, art teacher and girl scout leader I take these things seriously. But I have also seen innocent people charged with child abuse due to the misguided over - zealousness or plain nosiness of someone in the neighbourhood. So obviously this is something we have to be careful over. Even an accusation which turns out to be false can ruin an innocent person's life and reputation.

I think you are missing the point, Bruyere. What Karr revealed to the professor were fantasies of things he thought about doing to little girls. He did not (other than the JonBenet murder), report any actions he had actually taken with specific children. This case has absolutely nothing to do with mandated reporting of child abuse.

No one is required to report child abuse, or even suspected child abuse, simply because someone has heard a person express sexual fantasies regarding children. Child abuse requires that there be an actually abused specific child. An act of child abuse, not a thought, must have taken place, and it must be toward a specific child. Child Protective Services investigates only allegations of specific abuse to specific children--it is not their job to investigate the contents of an emotionally disturbed individual's mind.

As far as I have heard, there have never been specific complaints of child abuse lodged against Mr. Karr, although his teaching methods, in Thailand, were questioned because his approach was too intimidating and he was dismissed from his job for that reason. There has thus far not been any evidence that he ever actually abused any child, sexually or otherwise.

I can certainly understand why Mr Karr's sexual fantasies and comments made that professor and the Boulder D.A. nervous. No one wants to listen to that crap and no one wants to see an adult act out on such fantasies. But you simply cannot arrest a person just for having such sexual thoughts. The law requires that an action be committed which actually endangers, or imminently threatens to endanger, a child. And evidence of the act is required. There is no evidence to charge Mr. Karr with child abuse, or to even report possible child abuse by him, of a specific child, to any investigating agency. You do not arrest a person because of the thoughts or fantasies they have. You do not arrest people because a hypothetical crime might happen in the future. You have to wait until the crime occurs or is in progress. You arrest people only because of their actions.

Certainly, hearing someone confess to a murder, is reason to report such statements to the police. That's an entirely different matter than someone simply voicing sexual fantasies about children. By confessing, the person is admitting to an action, and, in this case, the action was a killing. Whether the D.A. should then have acted on the basis of this confession, without any other evidence to support the confession, is a matter still very much open to debate.