If this is the case, he really doesn't have an alibi. He was probably seen and recognized and knew he had to account for being there. That would mean a local if he was worried about being recognized or knew he already was. If he said he was not there and a witness put him there they would question him further. By being a witness (and the only one who knew for sure beside Libby and Abby what BG was wearing during the crime) he made the videotaped BG a separate person from himself. The video agreed with his description. He left the scene in different clothes and not disguised by a hoodie or hat etc. hence the 2nd sketch. They put so much time into first sketch because they thought they had an eyewitness when in reality, it was BG all along without his disguise. Crazy thought, but it fits with last press conference comments.