Did I mishear ?
At the start of the movie, as an intro to the Eisenheim's backstory, Chief Inspector Uhl says something like: "we know everything about him, we have spoken to everyone that ever knew him".
This seemed to clash with the "And then he went away (to who-knows-where) for 15 years until he showed up in Vienna" (paraphrased) line.
Did I mishear or was that a stupid piece of scriptwriting ?