Garrick paused.  I scarcely breathed, nor did I move my eyes, which were riveted on his face.  What was he going to reveal next?  Was he going to accuse someone in the room?

“Mr. Marshall,” he resumed with a smile toward me, “I am glad to say is quite normal and innocent of all wrongdoing—­in this instance,” he added with a momentary flash of humour.  “Commissioner Dillon also passes muster.  Mr. Warrington—­I shall come back to, later.”

I thought Violet Winslow gave a little, startled gasp.  She turned toward him, anyhow, and I saw that not even science now could shake her faith in him.

“Mr. Forbes,” he continued, speaking rapidly as I bent forward to catch every word, “incriminated himself quite sufficiently in connection with the gambling joint, the raid and the slanderous letter, so that I should advise him when this case comes to trial to tell the whole truth and nothing but the truth about his helping a gunman in order to further what proved a hopeless love affair on his own part.  Here, too, is a little vest-pocket gun that was found under such circumstances as would be likely to connect Forbes in the popular mind with the shootings.”

“My lawyer has my statement about that.  I’ll read—­”

“No, Forbes,” interrupted Garrick.  “You needn’t read.  Your lawyer may be interested to add this to the statement, however.  A pistol that has been shot off has potassium sulphide from the powder in the barrel.  Later, it oxidizes and iron oxide is found.  This weapon has neither the sulphide nor the oxide, as far as I can determine.  It has never even been discharged.  No, it was not the pistol found on Forbes that figured in this case.

“As far as that new-fangled gun goes, Forbes, it was a frame-up.  You were kidnapped by a man whom you thought was your friend, and it was done for a purpose.  He knew the situation you were in, your jealousy—­I won’t dwell on that here.  He held you at the house up in the valley.  You told the truth about that.  He did it, the man who wrote the letter, because he hoped ultimately to shift all the guilt on you and himself go scot-free.”

Forbes stared dumbly.  I knew he had known what was coming but had held back for fear of what he knew had always happened to informers in the circle to which he had sunk.

“McBirney,” continued Garrick, “your emotions, mostly astonishment, show that you have much to learn in this new business of modern detection, besides the recovery of stolen cars.”

Garrick had paused for effect again.

“And now we come to the keeper of a nighthawk garage on the West Side, a man whom they seem to call the Boss.  That is getting higher up.  I find that he points, according to this scientific third degree, to one whom I have for a long time suspected—­”

A dull thud startled us.

I turned.  A man was lying, face down, on the floor.