Irina & Vlad Lobatchev say in their book Dyatlov Pass keeps its Secrets, that Dyatlov met with Ignat Ryakin the deputy head of a local exploration company. They say that Ryakin provided the group with classified maps and provided them with an official travel document but they would have to do something for him.
If this is true, it might explain Dyatlov's behaviour during the latter part of the hike. However passing classified information to someone not cleared for it is a serious offence everywhere. So was he cleared for such material? The books references are in Russian Cyrillic (obviously)
Just wondering if anyone else has another source for the Lobatchev's statement.