So, why the decision to remove the victims' faces? (potential spoilers)
Perhaps this is better explained in the novel, and without giving away the identity of the killer, at the end of the day I couldn't understand why that person would go through the trouble of removing faces and fingertips instead of just leaving the corpses in the snow.
Since the victims are two Russians and one American, not some high-level government official, it's unclear (to me) what the killer had to gain from concealing their identities, not to mention the considerable risk of another skater discovering the facial mutilation in process.
I never heard of anyone who murdered by the rules