Wolf,
It may have belonged to Ltn
Arthur Rahn. (No doubt you are familiar with his Dr1...)
Rahn lived in the US and subsequently died in Redford, Michigan.
About three years ago I was contacted by his daughter (or grand-daughter, I'm not sure which at the moment). At the time she refered to Ltn Rahn's photograph/memorabilia collection from the war and how she wanted to have it preserved intact... i.e. donated to an aviation museum. IIRC Ltn Rahn's wife was still alive (!

and was still able to identify people, places etc in the photos !
The lady who contacted me identified herself as a lawyer living in Dallas.
I strongly suggested she document as much as possible and I even had an aero friend who lives near Dallas volunteer to meet and assist her further.
Here's the rub... She never got back to me !
Conclusion: An Arthur Rahn collection exists out there and may or may not have been donated to a museum... perhaps the USAF museum in Dayton ?
It was one of the few I recommended to contact.
I probably have her name and the name of the firm she worked for but it might take a bit of searching. Just a thought. The cigarette case might not be Rahn's... no?
VBR
Rod