So, what is the best way to find out if you are the victim?
Call IRS? (Assuming you haven't filed it yet) Check TurboTax? (Essentially filing yours and wait for it to be rejected?)
Maybe TurboTax should have a tool that checks against their system(based on SSN and some credit history questions, etc) to see if you(the fraudster in this case) has filed your taxes or not.