My great uncle disappeared after Vietnam. He killed his best friend playing with a gun when he was a kid and hadn't been the same after, had a bit of a death wish. Vietnam had made him even more morose and withdrawn, so when he vanished, the family just assumed the worst and figured he had gone and committed suicide or gotten himself killed one way or another.
20 years later, come to find out, he had moved to Mexico and started a family. My grandmother got a call from his teenage daughter, letting us know he had passed away. Stomach cancer. Nobody had any idea. Dude just lit out and severed ties without saying a word.