so is it possible he worked for the Polish Underground
For records of Polish A.K. you could try:
Dr. Krzysztof Stolinski - Chairman
The Polish Underground Movement (1939-1945) Study Trust (Polish:Studium Polski Podziemnej)
11 Leopold Road
London W5 3PB
Tel./Fax: +44 (0)20 8992 6057
They hold most of the Polish undeground movements records in their archives.
Also you should try the Polish Red Cross who you can contact directly.
Or you can try Der Internationale Suchdienst (ITS) in Bad Arolsen
The International Tracing Service
If you live in the US you can ask the USHMM to access the ITS archives as they have recently be granted access this might be quicker that ITS in Bad Arolsen, it took me two years to get a reply
from them as they have so many requests.
If you contact the German camp archives you most likely will have to prove you are related to the person you are seeking information about, this is quite normal and they usually will only send paper copies of any information found to your postal address. But you should also bear in mind that many camp records were deliberately destroyed (so as to hide evidence of their crimes) by the SS ahead of the advancing Red Army or Allied forces so records are incomplete. If a camp was liberated by the Red Army then quite often the surviving camp records were removed to the USSR after the war. German archives are usual very prompt in replying. You will get a reply quicker if you can write in German. Also write in Polish if contacting the Polish Red Cross.