Same thing happened to Ambrose Bierce in 1913 when he joined Pancho Villa and wrote about the battles before disappearing. He was never found.
I read that half a dozen journalists disappeared trying to get the scoop on the Khmer Rouge; they expected the Hanoi Jane treatment, and truly underestimated the evil of much more serious communists than the Viet Cong.
I read a science fiction story about this years ago. He goes to Mexico, falls in with some natives, gets cured of his ills, gets fat, gets killed and eaten by his hosts.
Author of "The Devil's Dictionary", very funny stuff. Mr. Bierce had a wicked wit.
Regards,
GtG