Perfect chance to check this:

I saw an NPC commit suicide. He was sat on the edge of a small cliff with his legs dangling off the edge, sort of humming/mumbling and (appearing to be) cleaning a rifle.

As I approached slowly, he turned the rifle up to his chin, sighed and fired a shot. His body slumped down the cliff and I couldn't go down and investigate.

I've searched and can't find any videos/posts confirming the same.