In the hypothesis of a criminal case, I think the hikers were behind their murderers who were locals from District 41 and followed their tracks until jan. 30 when the murderers turned right and crossed the Auspiya river.
In blue the intended route of the hikers, in red the route of the murderers, in green the actual route of the hikers:
Update : I don't think anymore that the murderers were locals from District 41 and I think now they used the route described by Chagin in his testimony : " I told them about it and advised them to go through the hundredth kilometer i.e. quarter, as there would be better to go via the road. But they did not listen to me, and left for 41st quarter and 2nd Northern mine