On February 2, 1959, nine students from the Ural Polytechnical Institute hiked the northern Ural Mountains in Russia. Each of their lives was claimed by what investigators finally determined to be “an unknown compelling force.” Organs and clothing were missing, radiation was discovered at the site, evidence of extreme panic was apparent, while records of the incident still remain missing. Although this case remains unsolved, scientists provide the following explanations for the tragedy: hypothermia, an avalanche, or an animal attack. Only one possible outcome can be correct, so which is it?

It is important to know that Igor Dyatlov and the rest of his party were experienced hikers. In other words, they knew what they were doing. This makes it very unlikely that they would have been so careless as to succumb to hypothermia. Even if they had fallen to the cold, hypothermia could not explain why Lyudmila Dubinia’s eyes and tongue were missing, along with the fact that high levels of radiation were detected on the corpses and three of the hikers had major bone fractures.

If an avalanche had been the cause of the tragedy, the bone fragmentation would make sense. However, none of the group’s bodies had exhibited any external wounds in regards to the broken bones, which seems physically impossible due to the severity of their injuries. The corpses would have been found mangled and cut if they were to have been crushed beneath an avalanche. However, most of the bodies were found as if they had fallen over, faces frozen in fear. Most importantly, no evidence of an avalanche was ever found at the campsite; there was a lack of debris or a pattern trail that the natural disaster would have left behind.

According to scientists, the only other possible explanation for the disaster of Dyatlov Pass was an animal attack. But this would fail to justify why the party—some of whom were completely naked—had sliced open the tent, their only shelter, and fled single file into the freezing darkness.

Conspiracy theorists provided their own theory to explain the unexplainable, a claim that the original investigators had never once considered or voiced publicly.

Some people suspected that the Ural Mountains was the site of a Soviet secret weapon experiment, containing what the public thought to be something of the paranormal as a result of the “strange flying spheres” that some of the police had viewed at the scene and the radiation. These theorists believed that the hikers fell victim to whatever weapon was being hidden in the mountains or by the military personnel protecting it.

How could such a barbaric theory make any more sense compared to the other causes of death?

Much of the incident was censored by the Soviets. Writer and journalist Yuri Yarovoi had been part of the rescue party and also had served as the official photographer during the search and the investigation. If anyone were to have known anything suspicious about the Dyatlov Pass incident and have evidence to condemn a Soviet cover-up, it would have been him.

Yarovoi had written the book Of the Highest Degree of Complexity that was inspired by his discoveries. However, he had little control over what he could publish; he was forced to change his ending multiple times as a result. After Yarovoi passed, all of his documentation on the Dyatlov Pass mysteriously disappeared, taking possible evidence of this weapon experiment to his grave.

Although no one knows what truly happened to those nine students in the Ural Mountains, it is clear that the cause of their deaths was an unworldly force, most likely still roaming the mountains.