“I suppose everybody has been handling that box?” asked Craig quickly.

A smile flitted across Fletcher’s features.  “I thought of that, Kennedy,” he said.  “I remembered what you once told me about finger-prints.  Only myself has touched it, and I was careful to take hold of it only on the sides.  The will was placed in this box, and the key to the box was usually in the lock.  Well, the will is gone.  That’s all; nothing else was touched.  But for the life of me I can’t find a mark on the box, not a finger-mark.  Now on a hot and humid summer night like last night I should say it was pretty likely that anyone touching this metal box would have left finger-marks.  Shouldn’t you think so, Kennedy?”

Kennedy nodded and continued to examine the place where the compartment had been jimmied.  A low whistle aroused us:  coming over to the table, Craig tore a white sheet of paper off a pad lying there and deposited a couple of small particles on it.

“I found them sticking on the jagged edges of the steel where it had been forced,” he said.  Then he whipped out a pocket magnifying-glass.  “Not from a rubber glove,” he commented half to himself.  “By Jove, one side of them shows lines that look as if they were the lines on a person’s fingers, and the other side is perfectly smooth.  There’s not a chance of using them as a clue, except—­well, I didn’t know criminals in America knew that stunt.”

“What stunt?”

“Why, you know how keen the new detectives are on the finger-print system?  Well, the first thing some of the up-to-date criminals in Europe did was to wear rubber gloves so that they would leave no prints.  But you can’t work very well with rubber gloves.  Last fall in Paris I heard of a fellow who had given the police a lot of trouble.  He never left a mark, or at least it was no good if he did.  He painted his hands lightly with a liquid rubber which he had invented himself.  It did all that rubber gloves would do and yet left him the free use of his fingers with practically the same keenness of touch.  Fletcher, whatever is at the bottom of this affair, I feel sure right now that you have to deal with no ordinary criminal.”

“Do you suppose there are any relatives besides those we know of?” I asked Kennedy when Fletcher had left to summon the servants.

“No,” he replied, “I think not.  Fletcher and Helen Bond, his second cousin, to whom he is engaged, are the only two.”

Kennedy continued to study the library.  He walked in and out of the doors and examined the windows and viewed the safe from all angles.

“The old gentleman’s bedroom is here,” he said, indicating a door.  “Now a good smart noise or perhaps even a light shining through the transom from the library might arouse him.  Suppose he woke up suddenly and entered by this door.  He would see the thief at work on the safe.  Yes, that part of reconstructing the story is simple.  But who was the intruder?”