"But you said yourself that Felix never came to the inn on that night," he objected. "So I thought, but it appears that I was mistaken. Fundy, the livery-stable keeper, told me that. Felix hired a horse from him on the 10th and 11th of June. On both occasions he did not return till midnight. Now, Francis was murdered on the 10th, and his corpse disappeared on the 11th. Felix is therefore responsible for both the murder and the concealment of the body." "That is purely circumstantial evidence." I laid down the arrowhead on the table. "This is proof positive," I said triumphantly. "With that piece of flint Francis was killed." "Really?" said Merrick skeptically, picking up the arrowhead. "With such a clumsy instrument he must have bungled the job considerably." "Not at all. That arrowhead is steeped in virulent poison." "The deuce!" cried Merrick, dropping it hastily. "Why did you not warn me of its danger? I might have cut myself and gone the same way as poor Francis Briarfield. How do you know the murder was so executed?" "I told you about the discolored wound in the palm of the right hand?" Merrick nodded. "Well," I continued, "that was the cause of death, as there was neither scratch nor violence on any other part of the body. I picked up that arrowhead in the fireplace of the dining room of the Fen Inn, where it had doubtless been thrown by Felix after the committal of the crime." "Where did he get the arrowhead?" "That is just what puzzled me for a long time. Fortunately, I remembered that the entrance to Bellin Hall was decked with a perfect armory of savage weapons. I made an excuse of looking at the picture gallery, and so gained admission to the Hall." "Did you find anything likely to confirm your suspicions?" "Yes! I found that an arrow had been removed from the wall." "How could you tell that?" "Because the weapons were arranged in patterns, and one of the patterns was incomplete. Moreover, on comparing that arrowhead with those on the wall I found it was precisely similar in appearance." "Humph," said Merrick thoughtfully, "there is only one deduction to be taken from all this. Felix stole the arrowhead, and, knowing it to be poisoned, rode off to the Fen Inn to kill his brother. He is a clever scoundrel." "Very clever indeed," I answered dryly; "but for you, Merrick, he would have baffled me altogether." "I think you have him this time," said Merrick, laughing. "Now, what do you intend to do next?" "Have the pool dragged for the body and Felix Briarfield arrested." "Before doing so it would be advisable to find Rose Strent or her father." "Why so?" "Because they only can give positive evidence as to the committal of the crime. Failing them, Felix may slip through your fingers." "They won't show up or give evidence for their own sake." "In that case they must be found and forced into confession," said the doctor quickly. "And what about Felix and Miss Bellin?"