Winters who had been studying the room while we got our bearings picked up a queer-looking revolver from the floor. As he held it up I could see that along the top of the barrel was a long cylinder with a ratchet or catch at the butt end. He turned it over and over carefully.
“By George,” he muttered, “it has been fired off.”
Kennedy glanced more minutely at the body. There was not a mark on it. I stared about vacantly at the place where Winters had picked the thing up.
“Look,” I cried, my eye catching a little hole in the baseboard of the woodwork near it.
“It must have fallen and exploded on the floor,” remarked Kennedy. “Let me see it, Winters.”
Craig held it at arm’s length and pulled the catch. Instead of an explosion, there came a cone of light from the top of the gun. As Kennedy moved it over the wall, I saw in the center of the circle of light a dark spot.
“A new invention,” Craig explained. “All you need to do is to move it so that little dark spot falls directly on an object. Pull the trigger—the bullet strikes the dark spot. Even a nervous and unskilled marksman becomes a good shot in the dark. He can even shoot from behind the protection of something—and hit accurately.”
It was too much for me. I could only stand and watch Kennedy as he deftly bent over Schloss again and placed a piece of chemically prepared paper flat on the forehead of the dead man.
When he withdrew it, I could see that it bore marks of the lines on his head. Without a word, Kennedy drew from his pocket a print of the photograph of the smudge on Schloss’ door.
“It is possible,” he said, half to himself, “to identify a person by means of the arrangement of the sweat glands or pores. Poroscopy, Dr. Edmond Locard, director of the Police Laboratory at Lyons, calls it. The shape, arrangement, number per square centimeter, all vary in different individuals. Besides, here we have added the lines of the forehead.”