"It's very likely too simple for me," Hemingway explained. "I was hoping you'd hit on it."
The Sergeant ignored this. "If only we had some finger-prints to help us!" he said. "But everything was gone over so carefully, it doesn't seem to be any use prying that line again. I did think we might have got something from the dagger, but the hilt was as clean as a whistle. And it was plain the other dagger hadn't been toniched, nor the sheath of the one he used. Well, we saw how easily it slipped in and out of the sheath, didn't we? I could have drawn the blade out without touching the sheath, if I'd wanted to, when I took the whole thing down. In fact, now I come to think of it, I never used my Ieft hand at all, and I'll bet he didn't either."
"Just a moment!" said Hemingway, frowning. "I believe you've got something!"
"Got what, sir?"
"Your left hand. Do you remember just what you did do with it when you were up on that chair?"
"I didn't do anything with it, barring -"The Sergeant stopped, and his jaw fell. "Good lord!"
"When you stretched up your right hand, to take the knife down, you steadied yourself with your left hand against the wall. And that, my lad, is ten to one what kind Uncle Joseph did too, without thinking about it any more than you did! Come on, we've got to get hold of the finger-print boys!"
The Sergeant rose, but he had been thinking deeply, and he said: "Hold on a minute, sir! That's raised a point in my mind. I had to stretch up a good bit to reach that knife. Joseph couldn't have got near it, not on a chair."
"Then he didn't use a chair," replied Hemingway impatiently. "I never met anyone like you for trying to throw a spanner in the works!"
"What did he use, then?"