|NKVD prisoner massacres|
|Location||Occupied Poland, Ukrainian SSR, Byelorussian SSR, the Baltic states, Bessarabia|
|Prisoner victims||In excess of 100,000|
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, primarily Poland, Ukraine, the Baltic states, Bessarabia and other parts of the Soviet Union from which the Red Army was withdrawing ahead of the German invasion in 1941 (see Operation Barbarossa). Estimates on the death toll vary between locations leading to a total of 100,000 or more, from 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 or managed to escape because the retreating Soviet executioners logistically could not pay attention to all of them.
With the invasion of Russia by German forces, the NKVD was responsible for evacuating prisons in the occupied regions. More than 140,000 prisoners were successfully evacuated by the NKVD. More than 9,800 were reportedly executed in the prisons, 1,443 were executed in the process of evacuation, 59 were killed for attempting to escape, 23 were killed by German bombs, and 1057 died from other causes.
The NKVD and the Red Army killed prisoners in many places from Poland (e.g. Białystok) to Crimea. Immediately after the start of the German invasion of the USSR, the NKVD commenced the execution of large numbers of prisoners in most of their prisons, while the remainder was to be evacuated in death marches. Most of them were political prisoners, imprisoned and executed without a trial. The massacres were documented by German authorities and used in anti-Soviet and anti-Jewish propaganda. With few exceptions, the huge group of prisoners of Western Belarus and Western Ukraine was either marched eastwards or executed. After the war and in recent years, the authorities of Germany, Poland, Belarus, and Israel identified no fewer than 25 prisons whose prisoners were killed—and a much larger number of mass execution sites. Among the notable cases of such mass execution of prisoners were the following:
By 1941, a large part of the ethnically Polish population, subject to Soviet rule for two years already, had already been deported off the border regions to remote areas of the Soviet Union. Others, including a large number of Polish civilians of other ethnicities (mostly Belarusians and Ukrainians), were kept in provisional prisons in the towns of the region, where they awaited deportation either to NKVD prisons in Moscow or to the Gulag. It is estimated that out of 13 million people living in the pre-war Eastern Poland, roughly half a million of people were arrested, more than 90% of them being males. Thus approximately every tenth adult male was imprisoned at the time of the German offensive. Many died in prisons from torture or neglect. Methods of torture included scalding victims in boiling water and cutting off ears, noses and fingers. Timothy Snyder estimates that the NKVD shot some 9,817 imprisoned Polish citizens following the German invasion of the USSR in 1941.