Curt Siodmak, Robert Siodmak's brother, a novelist and screenwriter;
In Film Noir: The Dark Side of the Screen, Foster Hirsch said that Siodmak's characters "are nurtured by their obsessions."
The German version was the last German film that either Siodmak or Peter Lorre, who played a secondary character, would make in Germany before the war.
The story was written by Robert A. Stemmle, Curt Siodmak and Max W. Kimmich, who also presented the idea to this film to his colleagues.