Ah yes, the favorite place of Communism regime to dispose of unwanted citizens, instead of just hanging them.

It was usually a death sentence, be it for uranium ore, brutality of the guards or inhumane conditions. Crimes varied, often political opponents of hardline communists (including less radical ones), or being in domestic/foreign resistance against nacism during WWII.

Quite a few folks who fought for allies ie pilots in Battle of Britain, went home as heroes and ended up there. Sad times