“How did you get hold of the cunning scoundrel?” asked Rolfe.  “I’ve had his wife’s shop watched day and night, as I’ve said.  I made sure he would try to communicate with her sooner or later, but he didn’t.”

“It was Joe who found him,” said Crewe.  “I knew you were watching Mrs. Hill’s shop, so it was superfluous for me to set anybody to watch it.  Besides, I didn’t think Hill would visit his wife or attempt to communicate with her, for he would think that the police, if they wanted him, would be sure to watch the shop.  I tried to consider what a man like Hill would do in the circumstances.  He had no money—­I knew that—­and, so far as I was able to ascertain, he had no friends who were likely to hide him.  Without friends or money he could not go very far.  Finally it occurred to me that he might be hiding somewhere in Riversbrook—­either in that unfinished portion of the third floor, or in one of the outbuildings.  He knew the run of the rambling old place so well.  Have you ever been over it carefully?  No.  Well, there are several good places in the upper stories where a man might conceal himself.  I put Joe on the job, and after watching for several nights Joe got him.  Hill had made a hiding place in the loft above the garage.  It appears that he subsisted on the stores that had been left in the house; he was able to make his way into the main building through one of the kitchen windows.  He was on one of these foraging expeditions when Joe discovered him—­emaciated, dirty, and half demented through terror of the gallows.”

“So that is how you got him!” said Rolfe.  “I never thought of looking for him at Riversbrook.  Sometimes I am inclined to agree with you that he had no nerve for murder.  But an unpremeditated murder doesn’t want much nerve.  He might have done it in a moment of passion.”  Rolfe was endeavouring to take advantage of Crewe’s communicative mood and to arrive by a process of elimination at the person against whom Crewe had accumulated his evidence.

“It was not Hill,” said Crewe.  “The murder was committed in a moment of passion, and yet it was far from being unpremeditated.”

“You are trying to mystify me,” said Rolfe despairingly.

“No; it is the case itself which has mystified you,” replied Crewe.

“It has,” was Rolfe’s candid confession.  “The more thought I give it, the more impossible it seems to see through it.  Was Sir Horace killed before dusk—­before the lights were turned on?  If he was killed after dark, who turned out the lights?”

“He was killed between 10 and 10.30 at night,” said Crewe.  “The lights were turned out by the woman Birchill saw leaving the house about 10.30.  But she was not the murderer, and she was not present in the room, or even in the house, when Sir Horace was shot.  She arrived a few minutes too late to prevent the tragedy.  Turning out the lights was an instinctive act due to her desire to hide the crime, or rather to hide the murderer.”