During the Nazi invasion of Poland, the Germans also carried out attacks on Polish controlled building in the Free City of Danzig (Wolne Miasto Gdańsk), including the post office, which constituted extraterritorial Polish property.
Schenk began researching the events in 1993 and published a book, Die Post von Danzig: Geschichte eines deutschen Justizmords ("The Post Office of Gdańsk: History of a German judicial murder"), which led to the revision of the verdict.