“You wore no gloves when you clasped the handle of the knife you used to stab Ingelow, because Milhau had directed you to remove your gloves during the action of the play, and you couldn’t ignore his direction without rousing suspicion. In your character as a Russian detective, you had to wear heavy leather gloves—too heavy for such a delicate operation as stabbing Ingelow in a certain anatomical spot. But there was no danger of fingerprints, because you chose a knife handle that was elaborately grooved. Excitement and perhaps a recent dose of insulin made your palms perspire freely. The grooved surface of the knife handle rejected fingerprints, but it retained more perspiration than a smooth handle would have done. When a fly was attracted to the handle and ignored the bloodstained blade, I began to suspect the truth. The city toxicologist has already reported that he had found chemical traces of human perspiration and sugar on the knife handle. As soon as he subjects it to a spectroscope he will find some indication of butyric acid. This was the one fact Adeane knew that was not known to anyone else. He was the only witness present with the Inspector and myself when the fly alighted on the knife handle. He noticed it as we did and that cost him his life. This morning before rehearsal he told me in your presence that he had been reading about diseases of the pancreas at the medical library when he spoke of the suggestive effect on the body of such reading. He also mentioned Dr. Heiser’s book which he was carrying under one arm, and dropped a broad hint about the Fly who witnessed the murder of Cock Robin. Apparently he thought you could be bullied into helping his career. He wanted you to put two and two together—and you did. You knew from experience that diabetes was a disease of the pancreas, and you glanced through Adeane’s copy of Heiser’s book and saw that the only reference to flies concerned the Hindu method of diagnosing diabetes. You concluded as Adeane wanted you to, that he had read enough medical literature to recognize the symptoms of diabetes in you and that in some way the action of a fly had indicated to him that the murderer was a diabetic. But instead of allowing Adeane to blackmail you, you killed him; and he had so little realization of his danger that he gave you an opportunity to do so by playing
“Anyone who had just touched candy might have left sugar and perspiration on that knife handle!” protested Leonard.
“But not butyric acid as well. The knife handle had the same fruity odor as your breath. So did the handkerchief you dropped beside Pauline when you stabbed her tonight. There is enough acid on the handkerchief for it to be identified by chemical analysis. You must have wiped brow and neck and hands with it and—that will convict you of murder.”
“Without a motive?”
“You loved Wanda, didn’t you? That was why you introduced her to Milhau when she was unknown and gave her a chance on the stage. In the art gallery you said that Wanda’s allure was like an X-ray burn—a delayed reaction. You weren’t thinking of Rodney then—you were thinking of yourself. You had thought you could get over it, and you were finding that you couldn’t. Perhaps she wouldn’t let you. She didn’t like her victims to be cured. She was flirting with you as well as Rodney when Pauline and I watched her in the art gallery that afternoon. When you came back to New York after serving your prison term in Illinois you found she no longer cared for you or even pretended to do so. You were too shrewd to be taken in by the publicity romance Milhau staged between Wanda and Rodney. You spied on her as a jealous man will—as you did the morning you discovered her with me on the balcony—and so you unearthed something unknown to her other friends: her secret engagement to John Ingelow; and his pending divorce from Margot, which had come to a head while you were in prison. Yet you so masked your feelings that Wanda had no idea you even knew Ingelow by sight. He was younger, richer and more eligible than you, so you had no hope of supplanting him. Your old place as Wanda’s leading man was gone. Rodney was the rising star because he was young and attractive; yet you were the better actor. That was a bitter pill. You hated Rodney for that. You hated Wanda whom you had once loved for her fickleness and ingratitude. You were jealous of Ingelow. Since you couldn’t have Wanda yourself, you determined that Ingelow should never have her either; and you murdered him in such a way that Wanda and Rodney became the principal suspects. You arranged that cleverly by prompting Hutchins to tell Wanda the old story of Edward VII playing
