"His Christian name, I think," said the colonel after a moment's thought. "He went wrong at college and was sent down. Then he went to Paris and started to study art, and he got in trouble there, too. That's as much as he ever told me." "He had no brothers?" asked the commissioner. "None," said the colonel emphatically. "I am certain of that, because he once thanked God that he was the only child." "I see," the commissioner nodded; "you have formed no theory as to why he met his death or how?" "No theory at all," said the colonel, but corrected himself. "Of course, I've had ideas and opinions, but none of them has ever worked out. So far as I know, he had no enemies, although he was a quick-tempered chap, especially when he was recovering from a dose of 'coco,' and would quarrel with his own grandmother." "You've no idea why he was in London? Apparently he did not live here." The colonel shrugged his massive shoulders. "No, I couldn't tell you anything about that, sir," he said. "He was not an American?" asked the commissioner again. "I could swear to that," answered the colonel. There was a pause and he waited. "There's another matter." The commissioner spoke slowly. "I understand that you are being bothered by a mysterious individual who calls himself the Knave of Judgment." "Jack o' Judgment," corrected the colonel with a contemptuous smile. "Those sort of monkey tricks don't bother me, I can assure you." "I have my theories about the Jack o' Judgment," said the commissioner. "I have been looking up the circumstances of the murder, and I seem to remember that on the body was found a playing card." "That's right," said the colonel, who had remembered the fact himself many times, "the Jack of Clubs." "Do you know what that Jack of Clubs signified?" asked the commissioner, but the colonel could honestly say that he did not. Its presence on the body had frequently puzzled him and he had never found a solution. "There is a certain type of ruffian to be found, particularly in Paris, who affects this sort of theatrical trade-mark--did you know that?" asked the commissioner. The colonel was suddenly stricken to silence. He did not know this fact, in spite of his extraordinary knowledge of the criminal world. "These men have their totems and their sign manuals," said the commissioner. "For example, the apache Flequier, who was executed at Nantes the other day, invariably left a domino--the double-six--near his victim." This was news to the colonel too.