Remains aren't always found at the site of death. They may move (what archeologists and forensic anthropologists call "post-depositional position change) due to wind, rain, snow, falling trees, or the gravitational effects of sloping terrain. Even more likely - wild animals often scatter remains. Since only the skull was found it could be it was carried there by an animal and that is not the site of his death.
Good info, thanks. But more than the skull was found. From the last article: "...investigators responded to the park and were escorted to an area located off one of the trails where more human remains were discovered. " I suppose someone or an animal could have moved the entire body to its final resting place, or, the body has remained where it was when the person died.