Tibor Zolan's blackmail?
A bit of a naive question, I suspect! But, if Zolan was going to blackmail Lazlo, wouldn't he be implicating himself as well? Looking at it from a coldly practical standpoint.
After all, Zolan was scarcely less guilty in all those massacres in Hungary 40 years earlier.
One possibility is that Zolan was the 'camera man', so he didn't appear in the photos.