With this difficulty we arrive at the last and crucial phase of my investigation. Having the foregoing points clearly in mind, I spent the rest of the day before the inquest in talking to various persons and in going over my story, testing it link by link. I could only find the one weakness which seemed to be involved in Martin’s sitting up until 12.30; and since his having been instructed to do so was certainly a part of the plan, meant to clinch the alibi for Marlowe, I knew there must be an explanation somewhere. If I could not find that explanation, my theory was valueless. I must be able to show that at the time Martin went up to bed the man who had shut himself in Manderson’s bedroom might have been many miles away on the road to Southampton. I had, however, a pretty good idea already—as perhaps the reader of these lines has by this time, if I have made myself clear—of how the escape of the false Manderson before midnight had been contrived. But I did not want what I was now about to do to be known. If I had chanced to be discovered at work, there would have been no concealing the direction of my suspicions. I resolved not to test them on this point until the next day, during the opening proceedings at the inquest. This was to be held, I knew, at the hotel, and I reckoned upon having White Gables to myself so far as the principal inmates were concerned. So in fact it happened. By the time the proceedings at the hotel had begun I was hard at work at White Gables. I had a camera with me. I made search, on principles well known to and commonly practised by the police, and often enough by myself, for certain indications. Without describing my search, I may say at once that I found and was able to photograph two fresh fingerprints, very large and distinct, on the polished front of the right-hand top drawer of the chest of drawers in Manderson’s bedroom; five more (among a number of smaller and less recent impressions made by other hands) on the glasses of the French window in Mrs. Manderson’s room, a window which always stood open at night with a curtain before it; and three more upon the glass bowl in which Manderson’s dental plate had been found lying. I took the bowl with me from White Gables. I took also a few articles which I selected from Marlowe’s bedroom, as bearing the most distinct of the innumerable fingerprints which are always to be found upon toilet articles in daily use. I already had in my possession, made upon leaves cut from my pocket diary, some excellent fingerprints of Marlowe’s which he had made in my presence without knowing it. I had shown him the leaves, asking if he recognized them; and the few seconds during which he had held them in his fingers had sufficed to leave impressions which I was afterwards able to bring out.