Different people had numerous assumptions, gossips and misconceptions about the reasons of the accident and the accident itself. They came from the incomplete information, uncertainty of conclusions of the investigation and the general misunderstanding of specific nature of camping trips including environmental conditions.
Dozens of various «versions» are thought up. But in fact most of them were only assumptions which tried to explain some facts and events, but contradicted to other facts and events. These contradictions didn't allow to put all known facts together in an integral scene of events and to explain all unclear facts. To think up your own «version» of events turned out to be rather easy but it was much more difficult to prove it and to connect with known facts. Researchers didn't succeed in it and the accident was still covered with veil of secrets.
Among numerous «versions» there were also «absurd» ones which reflected the opinion of some citizens, authorities and even investigators. Before Dyatlov’s group has been found there were suggestions that the tourists could «run away abroad». "Such versions" could only belong to those who haven’t travelled even one kilometer through taiga with a backpack (to reach the sea Dyatlov’s group would have to cover the distance 4 times more than all their route). There was also an «internal» criminal «version» according to which the accident could happen because of some intragroup conflict, drunken brawl or fight «for girls». Such «assumptions» were met with indignation and resolute rebuff from the experts who knew very well the true worth of these statements.
There were «versions» mocking at obvious nonsense. For example, «Aktrida dwarfs» «versions» which said about «kidnapping of tourists by malicious «Aktrida dwarfs» living underground as well as the «Aryan version». «Aktrida dwarfs» version probably came from the legends about «the people «sikcherty» (сикхерти») who lived in Yamal in dwellings like «dugouts» or originated from stone dolmens a few hundreds of which had been found in the north of Sverdlovsk region and described by regional ethnographers, according to Alexey Slepukhin. These «versions-parodies» are barely laughing at those who take them seriously. Serious «versions» arise from the following statements:
1 – the accident was a «natural» accident caused by strong natural environmental influence and some actions of group on a route in the conditions of environmental pressure.
2 – the accident was a consequence of «technogenic» factors («technogenic accident») resulting from some technical impact from weapon tests – missile, vacuum, radioactive or technogenic actions in the process of mining or from factories activities (explosions, poison or combustible gases, etc.).
3 – the accident was caused by a criminal action ("criminal" accident) such as attack of criminals or a crime committed by authorities which killed the tourist group having mistaken them for a gang or in order to keep some «secrets» or to carry out criminal «experiments». All versions anyhow related to criminal or secrets keeping are «conspiracy» assumptions which connect the tragedy with some «plot» aiming to commit a crime and hide evidences and traces. This is a conspiracy theory.
A conspiracy theory is effective if the «plot» to commit a crime and to hide evidences can be proved by facts but in this case the question is who devised a plot and why. But without these facts the conspiracy versions are baseless and have to be avoided because trying to prove such version one has to give validity facts, i.e. names of conspirators and their motivation. If the elements and motives of crime cannot be proved a conspiracy theory becomes harmful because it distracts from true reasons of the accidents and disturbs to prevent them in future. And sometimes it becomes even dangerous because in this case it gives way to slanderous attacks.
4 – the accident was «abnormal», i.e. caused by the «unusual» event which has not been connected neither with «usual» natural, nor technical nor «criminal» events. The "UFO version", «versions» about the unusual (paranormal) natural phenomena ("infrasound", «fireball», «cold plasma») or the accidental poisoning «version» are considered to be these ambiguous and unsupported assumptions.
But ambiguous versions have not been proved by specific explanation about the cause of the accident and whether «UFO» or a "toxic substance» or an «anomaly» took place as well as under what circumstances it happened. As long as neither UFO traces nor any traces of poisoning, nor the evidence of the abnormal phenomena have not been found. The belongings, food and the first-aid kit of the lost group didn’t contain any chemicals which could «stir up their minds».
Since then the opinions of many (but not all) researchers about causes of accident divided into two main directions: natural accident or "technogenic and criminal" accident (conspiracy version). Supporters of natural accident said that Dyatlov’s group accident is a failure usual for tourists and it wasn't connected with secret weapons tests or any crimes. There were attempts to unite «natural» and «technogenic» versions but such attempts didn't succeed. Supporters of «natural» accident also didn’t come to complete agreement.
The master of sports on tourism Moisey Abramovich Axelrod proposed a version about an avalanche being a main cause of accident. He has built a connected scene of events and pointed to many peculiarities in behavior of Dyatlov’s team and details of events. His «avalanche version» also included the steps describing loss of equipment and subsequent freezing of Dyatlov’s group under the conditions of cold weather, wind and snowstorm. Axelrod thought that after descent of an avalanche and having been injured Dyatlov’s group were rescuing the wounded and tried to return to the camp but lost their way because of the dark and snowstorm. Their attempts to come back to the tent on the mountain opened to wind appeared to be doomed. Axelrod didn't refuse the «technogenic» causes of the accident believing that the descent of an avalanche could be externally stimulated by weapons tests or military maneuvers.
But some aspects of his «avalanche» version met questions and objections which had no answers. There were objections according to which the mountain slope was not rather steep and there was no trace of avalanche. Evidences of searchers and tourists also showed that there were no signs of the avalanche in this part of the mountain. They said that Northern Ural is a region that is not known for avalanches and there were no accidents caused by avalanches. It seemed that the «avalanche» version obviously didn’t correspond to the conclusions of forensic examination. After all, it looked like Dyatlov's team was so heavily injured that couldn’t go down. And the presence of 8–9 pairs of footprints on the slope proved that all group or almost everyone were going down in a file joining hands.
All in all Axelrod was not able to overcome all objections and explain all events of the accident up to the end and his «avalanche» version with avalanche and snowstorm hasn’t had any supporters among skilled tourists for a long time. The theory appeared in 1991 (was written and then published in 1993 in the article of the book by N.A. Rundkvist «Hundred days in the Urals», 1993), much later criminal case had been closed and wasn't considered like an «official version» of the investigation. This version didn't have sufficient evidences and strong protection against attacks of opponents that’s why it was necessary to work on it to strengthen it or to give up.
The versions about «infrasound» influence or attack of a rogue bear were put forward as «natural» versions. Actually these natural versions are versions about some «unusual», abnormal phenomena. And even now in TV programmes they try to explain that the accident was caused by «cold plasma» and some special type of «fireball», «infrasound» or other anomalies. These «versions» have always been and remain only assumptions which have no evidences and direct influence. The same can be said about «criminal» causes of accident, while there are no evidences there is no subject matter. After all, it is possible to think up everything. But it is necessary to prove only what actually took place and what is based on reliable facts and evidences.
So a number of natural and «criminal» versions got hung up without support because they failed any evidences and didn’t have any confirming facts. Criminal «versions» fell into this «hopeless» group: «mansiyskaya», «household quarrel» (a conflict in the team). And also acute alcoholism or any other substances poisoning, including toxic «gases» and «propellant fuel». As well as assumptions about «death squads or escaped convicts» along with attack of "special