NKVD prisoner massacres

The NKVD prisoner massacres were a series of mass executions committed by the Soviet NKVD secret police against prisoners in Eastern Europe during World War II.
The victims were mainly from Poland, Ukraine, the Baltic states, Bessarabia and other parts of the Soviet Union. The Red Army was withdrawing ahead of the German invasion in 1941 ("see Operation Barbarossa"). The death toll came to 100,000 or more. There were nearly 9,000 in the Ukrainian SSR, to 20,000–30,000 in occupied eastern Poland, now western Ukraine, to all Tartar prisoners in Crimea among other places. Not all prisoner victims (150,000 of them in total) were murdered; some were transported into the interior, others were abandoned in prisons or managed to escape because the retreating Soviet executioners could not attend to all of them.