Quote MommyofMaggie: Whatever it was, and it might have something to do with having his DNA on the man for I.D. purposes; I think he was planning on killing/having the man killed to pass of as himself, but he backed off when he saw the man's son; either because he couldn't bring himself to kill (another) child or he didn't want to deprive the little boy of his father.
Quote Bellydancing_Fool: I thought it could have been some body part as well..but for some reason, when Adam got the hug from the guy's son, he backed right out. I hope all will be revealed soon!
Quote njay: My speculation is that he gave an iris or something related to his eye which caused his condition to start in the first place. If this is the case he had planned to do something long before all his schemes took place.