I had figured he was working for Luthor, although I am intrigued by Sira's idea that it actually *is* Luthor. I don't think it is a coincidence that they were freed after Luthor took Clark aside for a private discussion. I think Lex got Clark to 'voluntarily' donate a tissue sample with the twin incentives of offering to free him and Lois (the latter being the chief carrot) and threatening to kill Lois if Clark didn't cooperate or if Clark subsequently told Lois that this Superman isn't the real deal.
Joy,
Lynn
