Photo taken from a roll of film found at the camp of the Dyatlov Pass incident (via Wikimedia)

In January of 1959, 23-year-old Igor Dyatlov led a group of eight young Soviet hikers, comprising seven men and two women and mostly university students, into the Ural Mountains, attempting to reach Mt. Ortorten from the small settlement of Vizhai. It took more than three months to locate all nine of their bodies.

They were found about six miles away from their destination, in a forest almost a mile away from their campsite, without their skis, shoes, or coats in approximately -30 degrees Fahrenheit weather. Two of them had fractured skulls, two more had major chest fractures, and one hiker was missing her tongue. Soviet investigators listed the cause of death as “a compelling natural force,” and abruptly closed the case not even a month later.

Skiers setting up camp at about 5. p.m. on Feb. 2, 1959. Photo taken from a roll of film found at the camp of the Dyatlov Pass incident (via Wikimedia)

Here’s what we know about the incident. Six of the skiers died of hypothermia and three died of injuries. They died separately — two of them were found under a cedar tree near the remains of a fire, while three others were found in intervals of hundreds of feet from the tree, and four more were in a ravine another 250 feet away. The two under the tree had burned hands. The four in the ravine weren’t found until May 4, three months after the incident. The dead seemed to have donated some of their clothing items to the living; Ludmila Dubinina’s foot was wrapped in a piece of Yuri Krivonischenko’s pants, while Semyon Zolotaryov was found wearing Dubinina’s hat and coat, and some garments had cuts in them, as though they were forcibly removed. Consistently, there were eight or nine sets of footprints in the snow, accounting only for the skiers and not suggesting another party’s involvement (on foot, at least). There was no sign of struggle or of any other human or animal approaching the campsite. There was a snowstorm the night of February 2, which is when it was determined, via their diaries, that they died.

A view of the tent as the rescuers found it on Feb. 26, 1959 (via Wikimedia

Their campsite was made on the slopes of Kholat Syakhl (Dead Mountain), at about 3,600 feet. All the travelers — eight of them in their early/mid-20s with Zolotaryov in his late 30s — were experienced mountaineers, having skied across frozen lakes and totally uninhabited areas to get there. Despite nasty weather and slower progress than they’d planned, their last diary entries reflected high spirits. Charmingly, in a very typical Soviet way of bonding, they even produced a little newspaper about the trip, which they titled The Evening Ortoten and which bore the headline: From now on, we know that the snowmen exist. It goes on to say, “They can be met in the Northern Urals, next to Otorten mountain.” (They were, it’s thought, probably jokingly referring to themselves.)

After the first five bodies were found, a legal inquest began, eventually determining that the cause of death was hypothermia. The deaths seemed kind of straightforward at first. Sure, these dead were in various stages of undress, including one in his underwear, but this was explained away as “paradoxical undressing,” which happens in about 25 percent of hypothermia victims, as the hypothalamus malfunctions and body temperature seems to rise when it’s really dropping. But then it got super weird.

article-imageMysterious 33rd photo from Yuri Krivonischenko’s film (via Wikimedia)

The skiers’ badly damaged tent, it was determined, had been cut open from the inside, and all of their stuff was still in it. Why were they dead of exposure if they’d had access to their winter gear BEFORE going out into the freezing winds? To all appearances, they appeared to have left the tent out of their own volition and in a hurry. Bizarrely, Zolotaryov fled the camp with his camera but not his gear. As well, Rustem Slobodin — who, along with Dyatlov and Zina Kolmogorova, seemed to have died in a pose indicating he was trying to return to the tent — had a small crack in his skull, but it was ruled that the elements were what killed him, not the fracture. No external wounds were discovered.

Things got really shaken up when the four bodies in the ravine were found and examined; both Dubinina and Zolotarev had fractured ribs, while Nicolai Thibeaux-Brignolles had a major skull fracture. One of the investigators compared the force required to injure a human so severely to that of a car crash. The injuries were absolutely not caused by force exerted by another human being. Once again, no soft tissue damage was observed, as though the skiers’ bodies were crushed by pressure. When Dubinina was found to be missing her tongue, the theory of another party’s possible involvement must have arisen again — Who would do this? Why? Or did another skier from the group cut it out? And where did it go?  — but there were absolutely no indications of other people having been nearby, apart from the other travelers in Dyatlov’s group, not even the native Mansi people sometimes known to inhabit the area. And, perhaps most baffling of all, some of the skiers’ clothing was found to contain significant levels of radiation.

Monument to the dead skiers (photograph by Dmitriy Nikishin)

Due to “an absence of a guilty party,” the inquest was closed in May of 1959, only a few short weeks after the last four bodies were discovered, and the files were archived and classified. When they finally became accessible in the 1990s, post-Soviet era, parts of them were missing.

Without any real, public answers to any of these freaky questions, all manner of insane theory flourished around the incident over the ensuing 50 years, but the Soviet government’s very sudden closing of the case seems to have made it the most popular culprit in the minds of the theorists. Orange spheres were sighted in the sky on the night the Dyatlov group died by campers about 50 miles away from the scene; some explained these away as R-7 intercontinental missile launches, seeing as the last campsite was located on the pathway from Balikonur Cosmodrone to Chyornaya Guba, a Soviet nuclear testing ground. Per the radiation found in the skiers’ clothing, some speculated that they drank melted contaminated snow. A 12-year-old eyewitness who attended five of the skiers’ funerals claimed that the bodies had a “deep brown tan.” And you can’t talk conspiracies (and radiation) without mentioning aliens and UFOs, of course. Some folks even blamed the “snowmen” referenced in the students’ newspaper.

Detail of the monument with photographs of the skiers (photograph by Dmitriy Nikishin)

To this day, a scientific explanation for the deaths of these nine people has yet to be nailed down. Manifold publications were inspired by the incident, some investigative journalism and some entirely fiction. The mountain pass where the skiers set up their last campsite was named for Dyatlov, and the Dyatlov Foundation, established by Yuri Kuntsevitch — none other than the child eyewitness at the skiers’ funerals in 1959 — still works to persuade the Russian government to reopen the investigation. The foundation operates the Dyatlov Museum in Ekaterinaburg as well, to commemorate the dead travelers and tell the story of their strange ends.

This article originally appeared as part of Atlas Obscura’s 31 Days of Halloween in 2013.