I saw bigfoot in the predator mission, but never saw him in free roam. I searched for 10-15 hours .... but I found nothing. I think it was only a texture/script for this mission. Rockstar playing with our minds. But if you find bigfoot first, i give you 50 $ and Red Dead Redemption version of xbox 360 or ps3 (at choice). Of course, I need a video evidence, not a photo.
EDIT: I changed my mind, I was too euphoric. If I do not find bigfoot in next two days, I will come back with this prize.