Staff of Luftwaffe

I’m trying to get more information of my great grandfather whos name was Karl Neugebauer and was a part of Hermann Göring’s staff. The Luftwaffe staff was enormous and I haven’t been able to find a list of people working there. His rank and work at Luftwaffe is unknown - even my grandmother doesn’t know as it was kept as a secret from his own family. Any hints where I could start searching?
Appreciate all suggestions, thanks.

Danny