The Sergeant considered the ventilator, and sighed. "I see what you mean, sir."
"Well, that's something, anyway. Head first, that's how he must have got in, and nothing to catch hold of inside. The inference is he squirmed in, dropped on to his head on the floor, picked himself up, not a penny the worse for wear, and walked in to murder the old man, who hadn't heard a sound."
"The door may have been shut. He may have been deaf."
"He'd need to be stone-deaf. Talk sense!"
"I don't see how anyone got in by that ventilator, sir," said the Sergeant, after thinking it over. "Looks as though he must have come in through the door after all."
Hemingway got down from the stool, and returned to the bedroom. "Very well. We'll take it that he did. For what it's worth, the body was found lying with its back to the door."
The Sergeant frowned. "Well, sir, what is it worth?"
"Nothing at all," replied Hemingway. "You can say that someone stole into Nathaniel's room without his knowing it, and stabbed him in the back; and you can just as easily say that he was facing the other way when he was stabbed, and staggered round before collapsing. May have been trying to get to that bell by the fireplace. I had a talk with the police-surgeon, and he tells me that a stab to the right of the spine, in the lumbar region, wouldn't kill a man instantaneously. So the position of the body doesn't help us much."
"Was the door locked before the murder, sir?"
"Nobody knows, seeing that nobody knows when he was murdered. If I was one to let my imagination run away with me, which I'm not, I should say Nathaniel locked the door himself."