Once inside the door, Sheridan drew from his pocket a thin, flat, narrow strip of metal. One end of it was plain. Little tooth-like projections had been filed along one edge at the other end. On the Special Agent’s desk Sheridan laid the piece of wax he had exhibited during his earlier visit. Beside the wax he placed the thin metal strip. Without a word the Special Agent picked up wax and metal and applied the one to the other. The end of the metal that had been filed into a key fitted exactly into the impressions of the desk key in the wax. “So that’s the story, is it?” said Mr. King, looking up. “A wax impression of my key and a false key filed from the pattern. It is needless to ask who did it. What I want to know is how you found it.” “That wasn’t an easy job,” said Sheridan. “There wasn’t much to go on, but the little we had proved to be sufficient.” “Sit down, and let me have the whole story,” said Mr. King, his keen face alight with interest. The Secret Service man motioned to Tom Smith to be seated and then drew a chair forward for himself. “Although circumstances pointed strongly to young Brown,” he said, “they were far from being conclusive. If we had had proof that Willie was about your office here at the time we know he was in the building during the particular luncheon hour when the papers were taken, we should have had a pretty tight case against him. With him in this room or at his desk, it would be impossible for another person to get to your desk without his knowledge. Hence it would follow that he must be the thief. But if he was in his wireless room, as he claims he was, and has since proved he was, there was nothing to prevent another person from slipping in here unseen, and opening your desk. So we had those two lines of investigation to pursue. My predecessor proceeded on the theory that Willie was likely the culprit and acted accordingly. And he had some reason to do so, too. For years you have kept valuable papers in your desk, untouched. New employees have come and old ones gone, yet nothing was ever taken. But now comes this new boy, and almost at the first opportunity for him to steal, the papers disappear. The desk was unlocked by a false key, of course; and we know that a little time previously Willie had the keys in his pocket when he left the building. He could easily have had a false key made. It really was a strong case.” “It certainly was,” said Mr. King. “I didn’t want to believe the lad was guilty, but I almost had to.” “Well,” went on the Secret Service man, “my predecessor worked along that theory and got nowhere. His open questioning, of course, told everybody who he was, and then his usefulness was gone. So the Chief put me on the job.” “I see,” said Mr. King. “Even I did not know you were on it until you came in with that wax.”