"A most mysterious affair," I went on. "They called me soon after three, and I came down here, only to find the poor old gentleman stone dead--stabbed to the heart." "Let me see him," my friend said in a sharp business-like tone, which showed that he intended to lose no time in sifting the matter. He had his own peculiar methods of getting at the bottom of a mystery. He worked independently, and although he assisted the police and was therefore always welcomed by them, his efforts were always apart, and generally marked by cunning ingenuity and swift logical reasoning that were alike remarkable and marvellous. I gave him a brief terse outline of the tragedy, and then, unlocking the door of the room where the dead man still lay in the same position as when discovered, allowed him in. The place was in darkness, so I drew up the Venetian blinds, letting in the grey depressing light of the wintry morning. He advanced to the bed, stood in the exact spot where I had stood, and where without doubt the murderer had stood, and folding his arms gazed straight and long upon the dead man's features. Then he gave vent to a kind of dissatisfied grunt, and turned down the coverlet in order to examine the wound, while I stood by his side in silence. Suddenly he swung round on his heel, and measured the paces between the bed and the door. Then he went to the window and looked out; afterwards making a tour of the room slowly, his dark eyes searching everywhere. He did not open his lips in the presence of the dead. He only examined everything, swiftly and yet carefully, opening the door slowly and closing it just as slowly, in order to see whether it creaked or not. It creaked when closed very slowly. The creaking was evidently what the under-housemaid had heard and believed to be the creaking of boots. The murderer, finding that it creaked, had probably closed it by degrees; hence it gave a series of creaks, which to the girl had sounded in the silence of the night like those of new boots. Ambler Jevons had, almost at the opening of his inquiry, cleared up one point which had puzzled us. When he had concluded his examination of the room and re-covered the dead face with the sheet, we emerged into the corridor. Then I told him of the servant's statement. "Boots!" he echoed in a tone of impatience. "Would a murderer wear creaking boots? It was the door, of course. It opens noiselessly, but when closed quietly it creaks. Curious, however, that he should have risked the creaking and the awakening of the household in order to close it. He had some strong motive in doing so." "He evidently had a motive in the crime," I remarked. "If we could only discover it, we might perhaps fix upon the assassin."