What did Ponyboy think happened the night of the killing and what was Randy’s response?

In Chapter 11, Ponyboy tells Randy that he killed Bob in the park and that Johnny was innocent. Randy shakes his head and says, "Listen to me, Pony. You didn't do anything. It was your friend Johnny that had the knife..." (Hinton 165) Ponyboy maintains that he was the one who killed Bob. Ponyboy has been traumatized by the recent violent events. He has convinced himself that Johnny is still alive and that he was in the fact the person responsible for Bob's death. Darry enters the room and tells Randy it is time for him to leave. Darry warns Randy never to mention Johnny's name in front of Ponyboy ever again. Darry knows his brother is still shaken up by the recent events and is not thinking straight.