Or is it?
This guy claims to know the reason for the Disappearance of Dennis Martin back in 1969. Apparently there these feral men in the mountains and one of them took young Dennis. Most likely to eat him. These wild men are not Bigfoot, they have been in the mountains long before Columbus landed.
He does say this does not explain all the other missing people in other National parks, but it is something that explains Dennis' disappearance for their area.
Here is a link to the video: https://www.youtube.com/watch?v=ILOUTgz1WcI