Pre- and post-mortem injuries in a mammoth carcass found at 72°N in the Yenisei River basin and a separate finding of a killed wolf of similar age indicate that some humans were hunting in the Far North, 10,000 years before any other evidence known before (Mousterian implements from Komi Republic, surely made by H. neanderthalensis).
My first hunch is that the authors of these killings were also Neanderthals of the same Arctic population as the one living in Komi Republic, across the Urals. Another possibility could be that they were related to Ust'-Ishim man, a H. sapiens specimen from c. 45 Ka BP from further south-west, in the Ob-Irtish rivers' basin or to people established in Altai, who belonged to various human species (H. heidelbergensis, neanderthalensis and sapiens), depending on period and specific site.
Vladimir V. Pitulko et al., Early human presence in the Arctic: Evidence from 45,000-year-old mammoth remains. Science 2016. Pay per view → LINK [doi:10.1126/science.aad0554]
AbstractArchaeological evidence for human dispersal through northern Eurasia before 40,000 years ago is rare. In west Siberia, the northernmost find of that age is located at 57°N. Elsewhere, the earliest presence of humans in the Arctic is commonly thought to be circa 35,000 to 30,000 years before the present. A mammoth kill site in the central Siberian Arctic, dated to 45,000 years before the present, expands the populated area to almost 72°N. The advancement of mammoth hunting probably allowed people to survive and spread widely across northernmost Arctic Siberia.