The assassin must have placed it there, since a man would scarcely do such a silly thing himself. Why it was placed there I can’t say, any more than I can guess why Sir Charles was murdered, or who murdered him. The affair is a complete mystery, as you must admit.”

Before the inquest and after the inquest, more people than the three men who had held the discussion in the presence of the dead, admitted that the affair was a mystery. In fact the evidence at the inquest only plunged the matter into deeper gloom. Tenson, acting on Darwin’s advice, sought the office of the tramp-steamer company—the Universal Carrier Line—in which the late Sir Charles was chief shareholder and director, to learn without any difficulty the whereabouts of Mrs. Brown, the mother of the drowned man. She proved to be an entirely different person to the woman who had given the name on the fatal night, being lean instead of stout, comparatively young instead of old, and rather handsome in an elderly way in place of being wrinkled and worn with grief. She declared that she had never been near Moon’s house on the night of the murder or on any other night. Mrs. Bolstreath, Lillian, the footman, and Dan all swore that she was not the Mrs. Brown who had sought the interview with Sir Charles. Therefore it was argued by everyone that Mrs. Brown, taking a false name and telling a false story, must have come to see Moon with the deliberate intention of murdering him. Search was made for her, but she could not be found. From the moment she passed out of the front door she had vanished, and although a description was published of her appearance, and a reward was offered for her apprehension, no one came forward to claim it. Guilty or innocent, she was invisible.

Inspector Tenson did not speak at the inquest of the gang about which Sir Charles had intended to converse with Mr. Durwin, as it did not seem to have any bearing on the case. Also, as Durwin suggested, if it had any bearing it was best to keep the matter quiet until more evidence was forthcoming to show that such a gang—whatever its business was—existed. Then the strange episode of the fly was suppressed for the same reason. Privately, Tenson informed Dan that he would not be surprised to learn that there was a gang of murderers in existence whose sign-manual was a fly, real or artificial, and instanced another gang, which had been broken up some years previously, who always impressed the figure of a purple fern on their victims. But the whole idea, said Tenson, was so vague that he thought it best to suppress the fact of the artificial fly on the dead man’s neck. “If there’s anything in it,” finished the Inspector, “there’s sure to be other murders committed, and the fly placed on the victim. We’ll wait and see, and if a second case occurs, we’ll be sure that such a gang exists and will collar the beasts. Best to say nothing, Mr. Halliday.”

So he said nothing, and Dan said nothing, and Durwin, who approved of the necessary secrecy, held his tongue. Of course there was a lot of talk and many theories as to who had murdered the millionaire, and why he had been murdered in so ingenious a manner. The post-mortem examination proved that Moon had died of snake-poison administered through the scratch on the neck, and the circumstantial evidence at the inquest went to show that he must have been taken unawares, while bending over his desk. Some people thought that Mrs. Brown was innocent because of the absence of the perfume; others declared she must be guilty on account of her false name and false story, and the fact that Moon was found dead a quarter of an hour after she left the house. No doubt, the circumstantial evidence was very strong, but it could not be said positively that the woman was guilty, even though she did not appear to defend her character.

So the jury thought, for they brought in the only possible verdict twelve good and lawful men could bring in: “Wilful murder against some person or persons unknown,” and there the matter ended for sheer want of further evidence.