"Subsequently the jury returned an open verdict and that abominable crime has remained unpunished until now. Though it appeared so simple and crude at first, it proved a terribly hard nut for the police to crack. We may say that they never did crack it. They are absolutely convinced that Reuben Levison and Mrs. Aaron planned to murder the old lady, but how they did it, no one has been able to establish. As for proofs of their guilt, there are none and never will be, for though they are perhaps a pair of rascals, they are not criminals. It is not they who murdered Mrs. Levison." "You think it was Ida Griggs?" I put in quickly, as the Old Man in the Corner momentarily ceased talking. "Ah!" he retorted, with his funny, dry cackle, "you favour that theory, do you?" "No, I do not," I replied. "But I don't see----" "It is a foolish theory," he went on, "not only because there was absolutely no reason why Ida Griggs should kill her mistress--she did not rob her, nor had she anything to gain by Mrs. Levison's death--but as she was neither a cat, nor a night moth, she could not possibly have ascended from a first floor window to another window on the half-landing above, and entered her own room that way, for we must not lose sight of the fact that her bedroom door was the next morning found locked on the outside, and the key left in the lock." "Then," I argued, "it must have been a case of ordinary burglary." "That has been proved impossible," he riposted--"proved to the hilt. No man could have climbed up the wall of the house without a ladder, and no man could have brought a ladder into that backyard without leaving some trace of his passage, however slight: against the walls, around the yard, there were creepers and shrubs--it would be impossible to drag a heavy ladder over those walls without breaking some of them." "But some one killed old Mrs. Levison," I went on with some exasperation--"she did not strangle herself with her own fingers." "No, she did not do that," he admitted, with a dry laugh. "And if the murderer escaped through the window, he could not vanish into thin air." "No," he admitted again, "he could not do that." "Well then?" I retorted. "Well then, the murder must have been committed by one of the inmates of the house," he said; and now I knew that I was on the point of hearing the solution of the mystery of the five diamond stars, because his thin, claw-like fingers were working with feverish rapidity upon his beloved bit of string. "But neither Mrs. Aaron," I argued, "nor Reuben Levison----"