"Well, there was one! And this piece will fit that nick, or I'm a dumb-bell!" His eyes were dancing with delight. "Know what this means?"
"Y-yes. When the fellow slipped back the catch of this window he nicked the blade. Probably never noticed it. This piece fell to the floor and has been there ever since."
"Fell to the floor—yes. It isn't likely that it went neatly into the crack. It was swept there. Ever stop to think that the detective's best friend is the housemaid who scamps her work? Bless their little souls, they will sweep into cracks! But that isn't what I had in mind when I asked you if you knew what this means?"
"Maybe I could dope it out in time—"
"He opened this window with the dagger! Don't you get it?"
"My brain isn't hitting on all sixteen cylinders—"
"Listen. The assumption has been that he broke in here, took the dagger from the table where it lay handy, and forced Varr's desk. If he got the dagger after he entered the house, why did he then force the window with it?"
"Gee Joseph! It's a blind! He faked the breaking and entering to make it appear an outside job!"
"Yes." Creighton's face was solemn as he reclaimed his chip of steel and added the obvious corollary to Krech's deduction. "If it's not an outside job it must be an inside one. Somebody in this house took that dagger and notebook."
"I'll bet it was—!"