I knew deep down it wasn't, but it was my first thought i must admit.
I think i put too much thought into it:
i decided that he poses as Barty Crouch Jr in a parallel universe (just for shits and giggles or possibly to overturn the death eaters from the inside)...and therefore this is why we didn't get our hogwarts letters! we are simply in the wrong universe!
And as for J.K...a companion who visited this universe with him!
(it took me ages to decide weather this should be in the harry potter group, or the dr who group forums...but it turned more harry potterish in the end.) :)