If the DPI group were murdered, one person could not have done it alone, as he would have had to control all nine by himself.
I've been wondering if we can see evidence of how many killers there were (again, this is speculation, not a place for someone to say oh -- it was an avalanche) based on different "killing styles."
For example, Igor and Rustem and Zina were tied up, knocked to the ground, and left to freeze (killer #1).
Lyudmila, Zzolotaryev, and Tibo were viciously beaten (killer #2).
If you look at the situation this way, how do you see it? What "styles" can you see and how many killers?
I'm hoping that someone who has more understanding about killing evidence and forensic pathology than I do will share their thoughts.