"And they did so. You cannot have forgotten the singular knife which was found in the dead man's hand, a knife which certainly no sane man would choose for a weapon. It was, as Dr. Watson told us, a form of knife which is used for the most delicate operations known in surgery. And it was to be used for a delicate operation that night. You must know, with your wide experience of turf matters, Colonel Ross, that it is possible to make a slight nick upon the tendons of a horse's ham, and to do it subcutaneously, so as to leave absolutely no trace. A horse so treated would develop a slight lameness, which would be put down to a strain in exercise or a touch of rheumatism, but never to foul play."
"Villain! Scoundrel!" cried the Colonel.
"We have here the explanation of why John Straker wished to take the horse out on to the moor. So spirited a creature would have certainly roused the soundest of sleepers when it felt the prick of the knife. It was absolutely necessary to do it in the open air."
"I have been blind!" cried the Colonel. "Of course that was why he needed the candle, and struck the match."
"Undoubtedly. But in examining his belongings I was fortunate enough to discover not only the method of the crime, but even its motives. As a man of the world, Colonel, you know that men do not carry other people's bills about in their pockets. We have most of us quite enough to do to settle our own. I at once concluded that Straker was leading a double life, and keeping a second establishment. The nature of the bill showed that there was a lady in the case, and one who had expensive tastes. Liberal as you are with your servants, one can hardly expect that they can buy twenty-guinea walking dresses for their ladies. I questioned Mrs. Straker as to the dress without her knowing it, and having satisfied myself that it had never reached her, I made a note of the milliner's address, and felt that by calling there with Straker's photograph I could easily dispose of the mythical Derbyshire.
