I know I said I'm avoiding this thread, but I figured it was safe since tamidala was the only one to post after me, and I wanted to get this idea on the record so everyone will know how smart I am come Tuesday. ;-)
Maybe it's somebody we haven't seen, but who has been discussed extensively this season. How about Christian's FATHER??!!!
Think about it - the Carver is roughly the same height and weight as Christian. Genetics. And he's a serial rapist. Fits Christian's dad's profile perfectly!
So put that down as my prediction. The best part is that it could lead to one of the all-time greatest TV moments... The Carver leans over Christian, and in his electronically-altered voice tells him: "Christian... I am your father!!!"