“It wasn’t done. (Laughter.) The prisoner probably locked the door from the outside.  Those who broke it open naturally imagined it had been locked from the inside when they found the key inside.  The key would, on this theory, be on the floor as the outside locking could not have been effected if it had been in the lock.  The first persons to enter the room would naturally believe it had been thrown down in the bursting of the door.  Or it might have been left sticking very loosely inside the lock so as not to interfere with the turning of the outside key, in which case it would also probably have been thrown to the ground.”

“Indeed.  Very ingenious.  And can you also explain how the prisoner could have bolted the door within from the outside?”

“I can. (Renewed sensation.) There is only one way in which it was possible—­and that was, of course, a mere conjurer’s illusion.  To cause a locked door to appear bolted in addition, it would only be necessary for the person on the inside of the door to wrest the staple containing the bolt from the woodwork.  The bolt in Mr. Constant’s bedroom worked perpendicularly.  When the staple was torn off, it would simply remain at rest on the pin of the bolt instead of supporting it or keeping it fixed.  A person bursting open the door and finding the staple resting on the pin and torn away from the lintel of the door, would, of course, imagine he had torn it away, never dreaming the wresting off had been done beforehand.” (Applause in court, which was instantly checked by the ushers.) The counsel for the defence felt he had been entrapped in attempting to be sarcastic with the redoubtable detective.  Grodman seemed green with envy.  It was the one thing he had not thought of.

Mrs. Drabdump, Grodman, Inspector Howlett, and Sergeant Runnymede were recalled and reexammed by the embarrassed Sir Charles Brown-Harland as to the exact condition of the lock and the bolt and the position of the key.  It turned out as Wimp had suggested; so prepossessed were the witnesses with the conviction that the door was locked and bolted from the inside when it was burst open that they were a little hazy about the exact details.  The damage had been repaired, so that it was all a question of precise past observation.  The inspector and the sergeant testified that the key was in the lock when they saw it, though both the mortice and the bolt were broken.  They were not prepared to say that Wimp’s theory was impossible; they would even admit it was quite possible that the staple of the bolt had been torn off beforehand.  Mrs. Drabdump could give no clear account of such petty facts in view of her immediate engrossing interest in the horrible sight of the corpse.  Grodman alone was positive that the key was in the door when he burst it open.  No, he did not remember picking it up from the floor and putting it in.  And he was certain that the staple of the bolt was not broken, from the resistance he experienced in trying to shake the upper panels of the door.