Having checked my pocket size 1960 edition of English/Russian, Russian/English dictionary,
мошенник means swindler. So i agree that is the meaning of мошенник.
However, we have to look at this in the context of the timeline and documentation. Russian was the official language to record matters such as birth marriage and death registrations. I've seen many cyrillic records and very occasionally the cursive ' ш ' can look like the cursive ' ж ' (as in the 's' of 'usual'). On that basis the word wouldn't be мошенник but rather it would refer to someone of the Mosaic faith ie Moses which i take to mean Jewish.
The registrations follow the same format: name of the informant in cyrillic, and in the case of 'Russian Poland' and possibly other areas within the Russian Tsarist Empire, followed by the name in brackets in Polish/latin characters, and lastly the occupation in cyrillic. Very occasionally this reference to 'Mosaic' appears instead of the occupation.