“It should give a clue, Mr. Holmes.”

“It does give a clue. Whoever wrote that note was the man who brought William Kirwan out of his bed at that hour. But where is the rest of that sheet of paper?”

“I examined the ground carefully in the hope of finding it,” said the Inspector.

“It was torn out of the dead man’s hand. Why was someone so anxious to get possession of it? Because it incriminated him. And what would he do with it? Thrust it into his pocket, most likely, never noticing that a corner of it had been left in the grip of the corpse. If we could get the rest of that sheet it is obvious that we should have gone a long way towards solving the mystery.”

“Yes, but how can we get at the criminal’s pocket before we catch the criminal?”