Dyatlov Pass incident

The participants of the expedition had photographic equipment and kept diaries.

An excerpt from the article 39 facts about Dyatlov Pass incident

The entire course of the Dyatlov group's expedition, until their mysterious death, was documented by the young tourists. Some did it meticulously, while others paid less attention to this activity. Most likely, they owned five or six cameras. There is a very rich body of evidence in the form of photographs and diary entries. Countless enthusiasts of unexplained stories continuously rely upon gathered materials. Many of them are still trying to unravel the mystery of the Dyatlov Pass today.

The same cannot be said about prosecutors engaged in the investigation, except for Lev Ivanov, who was independent from his superiors, and for that was removed from the investigation. In 1992, he apologized to the families of the deceased claiming, that his superiors knew exactly what happened at the Dyatlov Pass, but were never interested in airing the truth.