During the years of the Great Patriotic War, the Finnish troops that invaded the Soviet land maintained a severe terror regime for almost three years. Thirteen Finnish concentration camps were operational in occupied Karelia. The first camp for Soviet citizens was established in Petrozavodsk on 24 October 1941. Of more than 64,000 Soviet citizens who had been taken to the Finnish concentration camps, more than 18,000 died, according to Finnish reports. According to information obtained by the Soviet Extraordinary State Commission for the Investigation of Atrocities by Finnish Occupants in 1941–1944, the Nazis conducted medical experiments on inmates and marked them not only with tattoos, but also branded them with hot iron. None of the Finnish military accused of war crimes was actually punished for crimes against humanity and war crimes.