The 'injured' McLeery was, in fact, Evans himself, and he acted very well. He made blood, that was supplied to him by his invigilator friend, pour down from his head. With a 'feeble' hand he got his handkerchief and held it to his bleeding head, to give the impression that he was actually injured and bleeding. In that process, he was able to hide his face from the eyes of the prison officers. He pretended to be in so much pain that he could hardly utter a coherent word. In this way, he concealed his voice and was able to dodge the officers. The moment he heard the suggestion of bringing in an ambulance, he interrupted and asked them to call the police. He offered them his help in tracing Evans. This was the part of his plan in which all the officers got trapped. He became successful in making them believe that the seriously injured McLeery was really trying to help them.