Read it through once

But my reward came at last. It was the print of the thumb of the forty-third man of Company C whom I had experimented on--Private Franz Adler. An hour before, I did not know the murderer's name, or voice, or figure, or face, or nationality; but now I knew all these things! I believed I might feel sure; the Frenchman's repeated demonstrations being so good a warranty. Still, there was a way to _make _sure. I had an impression of Kruger's left thumb. In the morning I took him aside when he was off duty; and when we were out of sight and hearing of witnesses, I said, impressively--