I watched this film at the weekend. I thought it was really good, but something has been bugging me. In one part of the murder investigation they go to the squat/home of the victims brother and his friends. The hunter (Jeremy Renner), points out tyre tracks to the fbi agent (Elizabeth Olsen), he shows her that they go all the way up the mountain, but no tracks come back. Can anyone tell me the relevance of this? I haven't had time to watch it again to see if I missed something, and it's really bugging me.