I'm trying to figure out who "Bauernfänger" is in Lang's M, what scene(s) he is in. He is supposedly played by the actor Theo Lingen. I haven't spotted him yet in viewing the film, and I can't find a reference to that name in the subtitles. "M" of course is Lang's trolling of the Nazi party.
He first appears in the film around 29 minutes in, lying on the sofa and smoking a cigarette and then doing card tricks at the table:
I found a trailer for the movie here and the cast is introduced starting at 1:35.
The character played by Theo Lingen is shown from 1:50 to 1:55. Here is a screenshot:
Unfortunately, I could not find a script so far. Thus, I can not really describe the scenes he is playing in. But maybe you recognise him now, when re-watching the film.