Mental health issues can be triggered by stress. It's entirely possible the guy had never snapped before, but being lost in the wilderness late in the day was enough to trigger an underlying condition.
I've witnessed some scary panic attacks in people where reality is chucked out the window by otherwise normal people with no past history. I've also witnessed some guys out in the woods realize they're lost, from my distant vantage point, and start to panic it was interesting to watch the initial reaction (of course we went and helped them get out of the area). Have a guy I know get lost in a thick area 200 yards from a road (granted it was so thick no GPS was working in there), and fire off 3 shots and we went in and got him....he'll never live that day down. But we also had to pack into the wilderness in steep country in the dark before to go find that same guy that missed his cut off to check in (found him hours later walking down a logging road on the other side of the area). Stuff happens in the brain when one is lost, disoriented, scared, etc. If there is an underlying mental health issue that is either known or unkown, it can be triggered with disastrous results during such stresses.
To the Op, I admire how you handled it. Great story.
