In Antigone, who does Creon think “buried” the body of Polyneices? Why did they do it?

In Antigone, Creon believes that one of the sentries has buried the body of Polyneices.  When the appointed sentry arrives to tell Creon that the body has been buried overnight, Creon becomes angry and says that he believes that one of the sentries has been seduced by a bribe to bury the body.  The sentry who reports this information has foreseen that Creon will likely accuse him of either burying the body or at least failing in his duty to guard the body, so he prefaces his statements by saying that he has had no hand in the crime.  Creon tells him that he must go out to find the traitor or else he will have to be responsible for the burial.  Creon is untrusting of the citizens of Thebes and does not feel secure in his position as King.  So he believes that one the sentries has been bribed to break his law and rule.