Professor Brierly, ignoring the interruption, pointed at former Police Commissioner McGuire. "This man, officer, probably is armed. You will find that the bullet that killed Amos Brown came from his weapon." One of the officers took a step toward the ruddy octogenarian. Jimmy stared, startled. Something was coming off that he did not understand. Three of the men sprang to their feet glaring at the principal actors to this strange scene. McGuire stood up, the blood gradually draining from his face. One of the police officers asked quietly, holding out his hand: "Are you armed, sir?" As McGuire's hand slowly went toward his side pocket, the officer said: "Give me the weapon, please." McGuire stared a long time at Professor Brierly, at his comrades, at the officers. He said: "Yes, I killed Brown. I killed him in self-defense." He drew out the weapon, slowly. Professor Brierly's voice, in the strained silence that had fallen on the group, sounded like a death knell. "You did not kill Goldberg and Tonti in self-defense. You did not engineer the killing of Schurman, Miller and Flynn in self-defense. You--_John!_" Professor Brierly's voice suddenly rose to a hoarse shout. The weapon in the hand of the stout, erect, pale man was slowly turning. Matthews sprang forward, but the officer reached McGuire first. There was a brief struggle for the weapon. Two officers led the man away. There was pain in Professor Brierly's eyes, and not the exhilaration to be found at the successful conclusion of an experiment in science; or the completed solution of a crime. He sat down and appeared reluctant to furnish the explanation that was expected of him. Suddenly Justice Higginbotham burst out: "But this is unthinkable, Professor. He was a comrade of ours. He was here with us all the time. He--you must be mistaken." He stopped and then continued more slowly, gravely: "Professor Brierly, you will have to give a very good reason for your astounding charge. You will have to remove every reasonable doubt. I am not talking in the legal sense now. This man was our comrade. I should as soon believe that I did this impossible, this terrible thing myself." A swift glance about the circle of faces showed Jimmy that they were all of the same mind. Professor Brierly said: "I understand. That is why I was reluctant to make the charge sooner, when we discussed it the other day. Some of you urged me, remember, to make a guess, which I could have done then. This terrible thing that happened this morning is something I could hardly foresee." He paused and went on. "Your number '14' Amos Brown died twenty-eight years ago, being survived by a son and grandson. The son died a short time later. Amos Brown the third, had no kin. But he was a self-sufficient youngster who managed pretty well. He entered the flying service in the World War and returned a bitter, disillusioned man.