Try checking the tax records. If they are not online you can call the tax assessor's office, it's all public record so they have to tell you. Sometimes certain addresses just don't show up on maps for some reason or another. Sometimes the entrance is on a side street while the home faces another and it can be very confusing.
I am not sure why you think this would be mortgage fraud. Perhaps you could explain a little more. Unless it's recorded incorrectly on the deed or mortgage documents, though, it's not a mortgage problem and even if it IS recorded incorrecty, unless someone is using that fact to cheat the bank out of money, I doubt it would rise to the level of actual fraud.