He produced them. I compared the writing with that of the note I had found near the safe. They were, as far as I could determine, identically the work of the same person.

Satisfied that I was on the right track, I caused a watch to be put upon the music teacher with the result that he was arrested as he was about to leave the city. He made a full confession.

“How did you guess it was a Frenchman who robbed my safe, and that he was accompanied by a pretty little dog?” inquired Mr. Camden.

“I found the cat had been killed by a dog, and his master afterward cut her throat with the hatchet to ward off suspicion from the dog; the dog drank the milk which had been provided for the cat. I found a note written in French and evidently dropped by the thief near the safe, and his dog was a pretty little animal because his master’s patrons, like yourself, would not tolerate the presence of any other kind, and you told me the dog always accompanied his master.”

The Key to the Mystery.

The most puzzling case upon which I ever worked was that of the murder of John Long. The facts are briefly these: Mr. Long, a wealthy, retired merchant, living at the home of his nephew, failed to answer the dinner-bell one day. He was a man who always prided himself upon his punctuality, and his failure to appear at dinner at the usual hour caused no little surprise. A messenger was sent to his room to call him. No response came to repeated knocks upon his chamber door. The door was locked. Fearful that something had happened to him, Mr. Brant—the old gentleman’s nephew—set about breaking down the door. This was no easy task, as the door was made of oak and fastened by a ponderous lock and large brass hinges. After considerable effort the door yielded to their blows and fell in. A horrible sight met the gaze of the anxious family. Mr. Long lay across the bed, cold and still in death, with his throat cut from ear to ear.

Had the old man been murdered? If so, how had the murderer entered the room? The old man was known always to keep his door locked. Besides, there did not appear to be anything missing. If it was a case of suicide, what had become of the implement with which the deed had been done? It was nowhere to be found. The old man always seemed in the best of spirits, and had every thing to live for.

If not suicide, then it was, of course, murder. Who, then, was the murderer?

It was my good fortune to be assigned to work up the case. I say good fortune because I like a difficult job, the more difficult the better, and this was one of the most difficult of all I had ever undertaken.

I examined the premises, and questioned the family and the servants in order to learn all I could about the murdered man, his habits, his financial affairs, etc. In particular I examined the room in which the foul murder had been committed. One of the windows was partially opened. This suggested the theory that the murderer might have gained access to the room by means of the window, but it was impossible for him to have done this in broad daylight, and the window was over 20 feet from the ground.