Rip you're talking about horrors of what was happening to people with less then respectful attitude - shame on you
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NKVD (what's become KGB later) troops weren't normally stationed behind combat troops - that's propaganda. They were, however stationed behind units formed from ex-prisoners coming from labour camps. Those had no other option but to go forward (often unarmed!!!) and "wash away their sins with blood" or die form either German bullet in the face or NKVD bullet in the back.
Every single combat unit had it's own "commissar" - a political officer. Those could report anyone they suspected in covardice or non-loyalty or basically whatever they felt like to NKVD with well known consequences. It's well known fact that many Soviet soldiers feared NKVD more then Germans - Germans wouldn't go after their families after they were killed - NKVD would...
The astounding success fo German army in 1941 could be contributed largely to the fact that after Stalin's purges in late 30s the Red Army was literally left with no command staff. And those who survived were looking over their shoulders all the time.
As for POWs - they were branded traitors and even if they escaped and made it across the front line they were sent to the camps
. One of the most spectacular escapes was when 11 POWs flew away from Pennemunde (V1/V2 test site) on a radar equipped He111. The plane was shot down by Russian AA, ditched with all escapees surviving only to be sent to the dreaded camps. The pilot - A. Devyatayev - was released from the camp after Stalin's death and named a hero...
On the other hand, America's own treatment of it's own citizens in the same period was less then exemplary - internment camps during the war and witch hunts after the war - weeding out misterious Commie agents... Something about casting the stone when without sin springs to mind...
