"I thought of that, but I don't know but what he might have come by it," argued the Sergeant.
"He might, but the odds are he didn't," retorted Hemingway. "Not one layman out of a hundred would know there was a tool for turning keys from the wrong side, let alone the name of it."
"Most people know there is a tool for doing that," persisted the Sergeant. "I don't say they'd know the name, but -"
"No; they'd just walk into the nearest ironmonger's and ask for a pair of forceps shaped a bit like eyebrow pluckers to open locked doors with, I suppose," said Hemingway, with awful sarcasm.
The Sergeant reddened, but said: "Well, that's an idea, anyway. Suppose the key was turned with a pair of eyebrow-pluckers?"
"I'm not going to suppose anything of the sort," replied Hemingway. "For one thing, they wouldn't be anywhere near strong enough, nor pliable enough; and for another, the grooving on them would be horizontal, instead of vertical, and wouldn't give them any grip on the key. Try again!"
"Well, sir, it's all very well, but if an oustiti wasn't used, what was? The murderer got into the room somehow. That we do know. Or if the door wasn't locked before the murder, it was after, and there's no sign the key was turned by the old pencil-and-string trick. It beats me."
"You're a great help," said Hemingway. "Ever asked yourself why the murderer took such precious care to lock the door after him?"
The Sergeant considered this. "I hadn't thought of that," he admitted. "Now you put it to me, sir, it does seem queer. Doesn't seem to be any point to it at all, unless it was just done to bamboozle us."
"Which it probably was," said Hemingway. "And I'm bound to say it's succeeding up to the present."