There was in fact a witness and he was questioned. It seems, however, that he said very little, from which Kreon infers that the man was traumatized by what he saw. The assumption underlying Kreon’s inference is quite natural; speech is clear except when interfered with by severe emotional strain. [Md] But would a roadside ambush strain the nerves of a man chosen to serve as escort to the king? Would not the additional fact, readily supposed by the audience, that there was but one assailant at the crossroads, have exposed the guardsman’s personal failure to protect the king? His very survival testifies to his cowardice, for he did not contribute to the struggle that cost the rest of the party their lives. Once Oidipous and Iokaste are married, the survivor has an additional reason to keep silent about what he saw, for his report would reveal that the queen has married her husband’s killer. The witness thus has at least two reasons to put a lock on his own tongue. Thus, where Oidipous assumes that a witness would discover the identity of Laios’ killer (or killers), the audience can see that questioning of the eyewitness would have yielded little information. Understanding has been hampered by the witness’s unreliability. [Mpew]
Lines 120-123
Oidipous: What’s that? The one fact might by logic lead
To several more120 if we but seize a brief reign over hope.121
Kreon: Bandits, he said, falling upon them killed him—
Not with one strength, but with all hands’ assembled might.77