NKVD prisoner massacres
The NKVD prisoner massacres were a series of mass executions of political prisoners carried out by the NKVD, the People's Commissariat for Internal Affairs of the Soviet Union, across Eastern Europe, primarily in Poland, Ukraine, Belarus, the Baltic states, and Bessarabia. After the start of the German invasion of the Soviet Union on June 22, 1941, NKVD troops were supposed to evacuate political prisoners to the interior of the Soviet Union, but the hasty retreat of the Red Army, a lack of transportation and other supplies, and general disregard for legal procedures often led to prisoners being simply executed.