reporter: zdenek mandrholec and jaroslav cibulka survived the czech gulag. they were political prisoners, sentenced to hard labor for treason because they had worked against the communist government. >> as a young soldier, i founded an anti-communist cell. there were 17 of us. we spied on an arms depot. and then i was arrested. reporter: jachymov is in the forests of the erz mountains, near the border to what was then east germany. after world war two, it was the soviets' primary source of uranium. the suffering of the forced laborers is documented in the city's museum. tens of thousands of political prisoners were crammed into barracks under wretched conditions. thousands died. >> guards with machine guns were posted in guard towers all around the camp's periphery. there were two fences. between them was the death strip. it was brightly illuminated at night. there was no escape. reporter: zdenek mandrholec worked in the uranium mine for six and a half years. jaroslav cibulka spent about nine years mining. neither had adequate nourishment or protective cloth