He is the winner of the "A life in Arkham" (or "Your face in Arkham", not sure) contest from Gamestop, where the first prize was to have your face in the game:
Pre-order a copy of Batman: Arkham
Asylum in any GameStop store between
September 8th and October 15th, and
you could win a chance to be
immortalized inside the infamous
Arkham Asylum. One lucky winner will
have his or her face and likeness
created as an in-game character,
locked inside of Arkham Asylum for the
rest of their days.
So he's not a known villain, only a player integrated in the game. This explains also why he seems more detailled, he is made from actual photos (of the face, at least).
I can't find correct sources for this, only a few posts on some forums, because the original GameStop page is not valid anymore.