Answer:
Oedipus heading a murder investigation and extending the applicability of punishment are examples of dramatic irony in "Oedipus Rex" by Sophocles (495 B.C.E. - 405 B.C.E.).
Specifically, dramatic irony refers to an incomplete or incorrect understanding of a situation. The description fits Theban King Oedipus' actions in looking for the guilty in the murder of his royal predecessor, King Laius. For example, Oedipus finds himself at the head of the murder investigation that ironically will prove him to be Laius' killer. Additionally, he extends the punishment of the guilty to all who have, but do not share, information and all who harbor or help the guilty even if they be members of the royal household. Oedipus does not realize when he gets so carried away with zeal that he deprives himself of any hope for pardon or mitigating circumstances once his crime becomes known and is judged.