When their camp was discovered, their shops were discovered open from the inside, and they wore very little clothing (in Russia, in winter).
It gets weirder. The bodies were stained orange with massive internal injuries by a force that a doctor who studied the incident compared to that of a car accident. There were no signs of fighting, despite victims with fractured skulls, broken ribs and a woman who lost her tongue, eyes and other parts of her face. As you can imagine, all sorts of theories about the cause of the deaths have been proven over the years, but the final verdict was that the hikers died of a "convincing natural force". And what does that mean? Never something so murky has been so horrible.
This is a mystery that will never be solved.