"I must take plaster casts of those prints before it rains," said Galloway. "They are far too valuable a piece of evidence to be lost. They form the final link in the case against Ronald." "You regard the case as conclusive, then?" said Colwyn. "Of course I do. It is now a simple matter to reconstruct the crime from beginning to end. Ronald got through Mr. Glenthorpe's window last night in the dark. As the catch has not been forced, he either found it unlocked or opened it with a knife. After getting into the room he walked towards the foot of the bed. He listened to make sure that Mr. Glenthorpe was asleep, and then struck the match I picked up near the foot of the bed, lit the candle he was carrying, put it on the table beside the bed, and stabbed the sleeping man. Having secured the money, he unlocked the door, carried the corpse out on his shoulder, closed the door behind him but did not lock it, then took the body downstairs, let himself out of the back door, carried it up here and cast it into the pit. That's how the murder was committed." "I agree with you that the murderer entered through the window," said Colwyn. "But why did he do so? It strikes me as important to clear that up. If Ronald is the murderer, why did he take the trouble to enter the room from the outside when he slept in the next room?" "Surely you have not forgotten that the door was locked from inside? Benson says Mr. Glenthorpe was in the habit of locking his door and sleeping with the key under the pillow. Ronald no doubt first tried to enter the room by the door, but, finding it locked, climbed out of his window, and got into the room through the other window. He dared not break open the door for fear of disturbing the inmate or alarming the house." "Then how do you account for the key being found in the outside of Mr. Glenthorpe's door this morning?" "Quite easily. During the struggle or in the victim's death convulsions the bed-clothes were disarranged, and Ronald saw the key beneath the pillow. Or he may have searched for it, as he knew he would need it before he could open the door and remove the body. It was easy for him to climb through the window to commit the murder, but he couldn't remove the body that way. After finding the key he unlocked the door, and put the key in the outside, intending to lock the door and remove the key as he left the room, so as to defer the discovery that Mr. Glenthorpe was missing until as long after his own departure in the morning as possible. He may have found it a difficult matter to stoop and lock the door and withdraw the key while he was encumbered with the corpse, so left it in the door till he returned from the pit. When he returned he was so exhausted with carrying the body several hundred yards, mostly uphill, that he forgot all about the key. That is my theory to account for the key being in the outside of the door."