“You are like Mr. Raymond. You take it for granted that what was heard at nine-thirty was Mr. Ackroyd’s voice speaking into a dictaphone. But consider this useful invention for a little minute. You dictate into it, do you not? And at some later time a secretary or a typist turns it on, and the voice speaks again.”

“You mean⁠—?” I gasped.

Poirot nodded. “Yes, I meant that. At nine-thirty Mr. Ackroyd was 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?”