The art of shedding light on gifts with possible Nazi ties The Museum of Fine Arts in Bern investigates the origins of an important donation by Georges F. Keller, and how certain works came to be in the collection. Last year, the Kunstmuseum's provenance researcher came across an archival document linking Keller to Etienne Bignou, a Frenchman now considered a "red-flag" dealer because he traded art with Germans in Nazi-occupied Paris.