"What--those little marks--a clue?" asked a voice behind us.

I turned and saw Elaine, looking over our shoulders, fascinated.
It was evidently the first time she had realized that Kennedy was
in the room.

"How can you tell anything by that?'" she asked.

"Why, easily," he answered picking up a brass blotting-pad which
lay on the desk. "You see, I place my finger on this weight--so. I
dust the powder over the mark--so. You could see it even without
the powder on this glass. Do you see those lines? There are
various types of markings--four general types--and each person's
markings are different, even if of the same general type--loop,
whorl, arch, or composite."

He continued working as he talked.

"Your thumb marks, for example, Miss Dodge, are different from
mine. Mr. Jameson's are different from both of us. And this
fellow's finger prints are still different. It is mathematically
impossible to find two alike in every respect."

Kennedy was holding the brass blotter near the bust as he talked.

I shall never forget the look of blank amazement on his face as he
bent over closer.

"My God!" he exclaimed excitedly, "this fellow is a master
criminal! He has actually made stencils or something of the sort