Did SAR employ tracking, cadavar, AND air scent dogs? I didn't realize til I read up on it that scent dogs but they only follow a human scent. They don't sniff the belongings of a missing person first. That fact obviously complicates things when other people were nearby. Whose scent are they following? Could be anyone's! I would think that since GGP, IR, and parents were the last at the campsite (before the searchers and after Deorr disappeared) that an air scent dog would most likely follow the scent of the more recent humans in the area. I guess it's possible that someone carried, as opposed to being dragged by an animal, him outside the search perimeter, however far that could be.
Yet...
Air-scent handlers generally don't do discrimination/trailing work with their dogs, instead letting the dogs find and report on any human who is in the area. In practice, this is not usually a drawback: anyone in the area is a potential witness with information about the search subject, and so needs to be interviewed. On the other hand, discrimination-trained air-scenting dogs can be a particularly flexible, useful SAR resource.
An air-scenting dog's lack of specificity can be a problem in a highly contaminated area. If a search area isn't cleared of hunters, hikers, or other searchers (the time necessary is highly dependent on local conditions), a dog team can waste a lot of time finding many wrong people, or even pockets of residual scent. More experienced dogs, especially if they've done some training in semi-crowded park and suburban environments, have some ability to compensate for these problems.