Is Oedipus guilty or innocent of the crime of killing his father and marrying his mother?
Well, yes, technically speaking, Oedipus did kill his father and marry his mother. Yet, as sordid as that all appears, it is not as simple a matter as contemporary references to the character would suggest. In Sophocles's play Oedipus Rex, or Oedipus the King, the titular figure is orphaned at a very young age through an act of his father, Laius, and does not know the identity of his parents until the ugly deeds are done years later. Laius was the king, but was killed by an individual who, it turned out, was Oedipus now grown up. Learning from Creon, the fate of the dead king, and guided by the knowledge that it had been prophesied that he would kill his father and sleep with his mother, Oedipus is slowly but steadily driven insane by the growing awareness of his guilt. Well before that awareness, however, he is determined to avenge his father's death, unaware of his role in bringing about that death. As he declares to Creon, "Whoever he was that killed the king may readily wish to dispatch me with his murderous hand; so helping the dead king I help myself."
The climactic exchange in Oedipus Rex occurs much later, when Oedipus confronts his wife/mother, Jocasta. This exchange is found in lines 700 and up. Oedipus is angered beyond reason by Creon's assertions. When Jocasta enters the scene, he presses her for details of Laius' murder. As Jocasta provides that information, Oedipus begins putting the pieces together, particularly the part where he encounters an individual at a certain crossroads and is complicit in that individual's death. As he begins to realize that he may indeed be guilty of his own father's death, as had been prophesied, he cries out, "O Zeus, what have you done? What have you planned for me?" This, however, is not the end. Oedipus resists the information, withdrawing into a state of denial, evident in his comment to "the messenger" that he "did not want to be my father’s killer."
What makes Oedipus' situation so complex is his belief that Polybus is his real father, when Polybus had, in fact, raised the abandoned child as his own. Polybus' death of natural causes gives Oedipus the reprieve from reality he craves, but he discovers in his conversation with "the messenger" that Polybus is not his natural father, reopening the possibility that he, Oedipus, killed his real father. And, this leads to the fateful confrontation with Jocasta that exposes him to the full measure of his "crime." Finally, in the exchange with "the messenger" and "the servant," Oedipus is enlightened as to the reality of his upbringing and marriage to Jocasta.
I think that it's really important to make sure that the discussion of Oedipus' predicament is done in the most sensitive of manners. I am not sure if it is as simple as one would like to presume that he is completely "guilty" or "innocent." Oedipus unknowingly kills his father, Laius, and marries a women that turns out to be his mother, Jocasta. Oedipus acts in a manner where he believes that he knows the truth, self- assured in that he has lived well and not engaged in any sinful behavior. Yet, through fated revelation and testimony, it does become evident that Oedipus is guilty of terrible acts. While this was not his intent, the redemptive element in his character and the drama is when he assumes the force of moral order and structure in a world where this might be absent. In this, Oedipus accepts and understands his role in what happens. In blinding himself, he loses physical sight, but gains a sense of insight that enables a full understanding of his own predicament and the sense of responsibility to help make right that which is wrong. In this, Oedipus accepts his own guilt, and seeks to better himself and those who are cursed enough to be his descendants.