I believe that Oedipus is innocent because he was given the fate that he would kill his father and marry his mother. He tried to avoid his fate by leaving Corinth since he thought his real father was the king of Corinth. Laius, who is his real father, even tries to get rid of him so his fate won't happen, but the servant would not get rid of him. He did not get to have free will because he never got a chance to leave his fate behind him. When he met Laius he did not know who he was and he defended himself from the servants. They were making him leave the road and he didn't want so they started attacking Oedipus. What are you supposed to do when someone attacks you. Not attack back? That is what he did and killed all of them including Laius. If you lack free will you can't be guilty because it would happen whether you like it or not. You can avoid it as much as possible but it will happen and that was what happen. You cannot escape fate which is the reason why Oedipus was not able to have free will during his life.