And this leads to one of the most important facts - the case files were opened on 6. February. It is clear that the authorities knew about the incident long before the tent was "discovered" by the search party.
The authorities knew about what had happened on February 6th, which was long before anyone in Ivdel or Sverdlovsk had any reason to suspect that anything was wrong. Not until February 12th did the relatives and friends of the nine start to think that something might have happened.
That means; they knew about the fate of the students, and had prepared for an "investigation" for almost a week before anyone in the Sverdlovsk area could have any reason to suspect anything.
Preparations for an investigation are not made the same day the written plans are made. Normally, some days are required for such preparation, with meetings and discussions. Since the preparations for an "investigation" were already completed on February 6th, the inescapable conclusion is that the Russian authorities knew about the fate of the nine unfortunates from the start.
Now, where does that leave us?