already dead. It was the dictaphone speaking—not the man."
"And the murderer switched it on. Then he must have been in the room at that minute?"
"Possibly. But we must not exclude the likelihood of some mechanical device having been applied—something after the nature of a time lock, or even of a simple alarm clock. But in that case we must add two qualifications to our imaginary portrait of the murderer. It must be someone who knew of Mr. Ackroyd's purchase of the dictaphone and also some one with the necessary mechanical knowledge.
"I had got thus far in my own mind when we came to the footprints on the window ledge. Here there were three conclusions open to me. (1) They might really have been made by Ralph Paton. He had been at Fernly that night, and might have climbed into the study and found his uncle dead there. That was one hypothesis. (2) There was the possibility that the footmarks might have been made by somebody else who happened to have the same kind of studs in his shoes. But the inmates of the house had shoes soled with crepe rubber, and I declined to believe in the coincidence of some one from outside having the same kind of shoes as Ralph Paton wore. Charles Kent, as we know from the barmaid of the Dog and Whistle, had on a pair of boots 'clean dropping off him.' (3) Those prints were made by some one deliberately trying to throw suspicion on Ralph Paton. To test this last conclusion, it was necessary to ascertain certain facts. One pair of Ralph's shoes had been
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