Personally, it doesn't seem that strange to me for Kevin not to report what he saw; we know nothing about him or his life. It obviously would have been the right thing to do. There is no excuse for not coming forward, because who knows how much time, effort, and money he might have saved the police. But maybe he'd experienced some sort of traumatic event in his life involving a police officer. Maybe he or a family member had had some sort of trouble with the law, and he was untrusting. The same goes for his girlfriend. It doesn't justify his actions, but I can see many scenarios in which they weren't flat-out malicious. Willingly involving himself in a case of a kidnapped child, when there are no other suspects, where there is evidence he was at the scene was probably a bit scary; we can see, now, that the case was handled poorly. Kevin, knowing the police officers, possibly expected no better from them. At the same time, I wonder how much effort even would have had to be put forth by the police to find Kevin.
Also, the night of a kidnapping, someone comes into the store Jacob was last seen at and randomly begins questioning bystanders: Are you a cop? Did you call the cops? It's almost disturbing that that itself wasn't reported prior to Kevin's story. Surely, the person behind the counter was questioned? Did he really not mention that incident to the police? It would have seemed suspicious to me. It really is a wonder Kevin wasn't a POI. His actions that night easily should have made him one. Why didn't those things interest the police?
