One more thing that points to Craig (minor clue)
At the interview after Paul is eliminated, Jon Kelley asks each player if they're the mole. He follows this up by saying that just one of them is lying.
Nicole: "No, I'm not the Mole."
Craig: "No, Mark is the Mole."
Mark: "No, I'm not the Mole."
Craig is the only one no to say I am NOT the Mole. Minor, I agree, but something. I don't beleive at any point that Mark is the mole, so that makes Craig the liar to me.