Or is it study the case? No pun intended - well since this is a crime drama or whatever you would call it, both summary lines work I think. What also seems to work is having this done in one language - although to do so, I am certain that certain people had to be dubbed. Yes Europe does not have one language everyone is talking (although I reckon English is quite widely known and spoken).
The international cast is quite impressive - at least you may know more than a few names if you call yourself a fan of that time and era. Heinz Rühmann in the lead role is quite the impressive feat in and of itself. The movie itself is ok or decent. But also quite predictable and may not have aged as well as some other crime movies. It is quite easy - not necessarily in a good sense.
Still I have seen worse movies and if you are into the crime aspect of it, you'll be entertained for sure - if you can suspend your disbelief of course.