“The window!” I said quickly.
“You, too, have my first idea. I imagined that the chair was drawn out so that something connected with the window should not be seen by any one entering through the door. But I soon abandoned that supposition, for though the chair was a grandfather with a high back, it obscured very little of the window—only the part between the sash and the ground. No, mon ami—but remember that just in front of the window there stood a table with books and magazines upon it. Now that table was completely hidden by the drawn-out chair—and immediately I had my first shadowy suspicion of the truth.
“Supposing that there had been something on that table not intended to be seen? Something placed there by the murderer? As yet I had no inkling of what that something might be. But I knew certain very interesting facts about it. For instance, it was something that the murderer had not been able to take away with him at the time that he committed the crime. At the same time it was vital that it should be removed as soon as possible after the crime had been discovered. And so—the telephone message, and the opportunity for the murderer to be on the spot when the body was discovered.
“Now four people were on the scene before the police arrived. Yourself, Parker, Major Blunt, and Mr. Raymond. Parker I eliminated at once, since at whatever time the crime was discovered, he was the one person certain to be on the spot. Also it was he who told me of the pulled-out chair. Parker, then, was cleared (of the murder, that is. I still thought it possible that he had been blackmailing Mrs. Ferrars). Raymond and Blunt, however, remained under suspicion since, if the crime had been discovered in the early hours of the morning, it was quite possible that they might have arrived on the scene too late to prevent the object on the round table being discovered.
“Now what was that object? You heard my arguments to-night in reference to the scrap of conversation overheard? As soon as I learned that a representative of a dictaphone company had called, the idea of a dictaphone took root in my mind. You heard what I said in this room not half an hour ago? They all agreed with my theory—but one vital fact seems to have escaped them. Granted that a dictaphone was being used by Mr. Ackroyd that night—why was no dictaphone found?”
“I never thought of that,” I said.
“We know that a dictaphone was supplied to Mr. Ackroyd. But no dictaphone has been found amongst his effects. So, if something was taken from that table—why should not that something be the dictaphone? But there were certain difficulties in the way. The attention of every one was, of course, focused on the murdered man. I think any one could have gone to the table unnoticed by the other people in the room. But a dictaphone has a certain bulk—it cannot be slipped casually into a pocket. There must have been a receptacle of some kind capable of holding it.
“You see where I am arriving? The figure of the murderer is taking shape. A person who was on the scene straightway, but who might not have been if the crime had been discovered the following morning. A person carrying a receptacle into which the dictaphone might be fitted——”
I interrupted.
“But why remove the dictaphone? What was the point?”