Vladek Sheybal (Russian KGB officer) was a real-life Polish partisan

Sometimes its interesting to read about actors who play in movies that mirror something of their actual real-life experiences. In the case of the KGB Police Officer, played by Vladek Sheybal, he really was a partisan fighter in Warsaw fighting against the Germans in WWII. According to his bio, he was captured twice, sent both times to concentration camps, but escaped. I have to wonder if he offered Milius or any of the others thoughts on his experiences to help them with verisimilitude.