“I will not deny that Deacon’s emphatic assertion that he had never even seen the rasp until it was exhibited at the inquest gave me a shaking. It did, and a bad one. I tested all the links in my chain, only to find each sound and the whole most obviously right—until this blind alley.
“Then it struck me, and I laughed at myself as those who read are probably already laughing at me. I saw that I was committing the grave error of underrating my man. I saw that so far from having received a check I had really been advanced.
“The finger-prints were on the handle of the rasp, and the handle—had I not been at much pains to prove it—had been separated from the blade by the murderer. The murderer—being an intelligent murderer—would certainly never have been such a fool as to let the fearsome and so-likely-to-be-remembered blade within Deacon’s sight. No, it was far more likely that he had disguised the handle as the handle of something else.
“Having got thus far, I progressed at speed. As what could he have disguised the handle? With efficacy, only as that of another tool. But he probably knew Deacon as a man who had no truck with tools. How, then, did he get the so-ordinary surroundings necessary to prevent awkward memories arising afterwards in the mind of Deacon? The answer is that they were there, ready-made, to his hand. In order to avoid obscurity, I will elucidate this.
“The indication all through had been that the murderer was a man accustomed to the use of carpenter’s tools. The murderer was an inmate of the house. Put one and two together and you will see that he would very possibly be known to the household as one who was ‘always messing about at that there carpent’ring.’ Deacon was also of the household, and would therefore see nothing unusual in, say, being asked to ‘hold this chisel (or gouge, or anything else you like) for just half a second.’ If this seem far-fetched, remember that from the beginning I felt the murderer as one who had been preparing his work for some long time.
“It was almost at the moment when I reached this stage of thought that a number of hitherto insufficiently substantiated suspicions which had been steadily massing in my mind suddenly rearranged themselves in such a manner as to become extra links in my chain of reasoning rather than the wild plungings of a mind tired of logic. This merging of reason with intuition (they are twins, those two) left me certain that I should know who I was trying to prove guilty if Deacon gave me the name of the man against whom these suspicions of mine had been directed in answer to the question: ‘Who, at any time within the last twenty-four hours preceding the murder, induced you to hold in your right hand an implement with a short, thick wooden handle of the same appearance as the handle you have seen in the wood-rasp?’
“You see, I had already learned that of the Abbotshall ménage four men frequently used, and had consequent access to, carpenter’s tools. These were the gardener, the chauffeur, the murdered man, and the guest from whom I had the information.
“Hoode, the gardener, and the chauffeur I disregarded. The first because he was not his own murderer; the second because at the time of the murder he was in bed at the Cottage Hospital in Marling; and the third because he has respectable and trustworthy friends to swear that he spent the evening of the crime in their company.
“Remained the guest—that enthusiastic amateur Dædalus—and he the man that from the beginning had excited those nebulous suspicions I have mentioned. He was living in the house at the time when the murder was committed. He was, by his own showing, an amateur carpenter of experience and enthusiasm. (Early he simulated ignorance as to the name of a wood-rasp. Later, by his voluntary statement, he showed that he could not have been ignorant of it. This was the only slip he made when talking with me.)
“Before I took opportunity to ask Deacon the all-important question, I did much and thought more. With one exception, these thoughts and actions are proper to the next part of this report, and accordingly are dealt with there. The exception is this:—