Free QED by Ellery Queen

leaving behind a bread-and-butter note. He did not check back in to the Hollis, the savor having for now gone out of Wrightsville; but he had a couple of hours to kill before plane time, and he killed them, appropriately, at police headquarters.
    â€œEllery!” Chief Newby greeted him, rising and seizing his hand. “I was hoping you’d drop in. I never did get to thank you properly. That was a slick scene you put on last night. You told a real whopper.”
    â€œI may have told,” said Ellery soberly, “several.”
    â€œYou said you knew what Ellen knew.”
    â€œOh, that. Yes, of course. But I had to get her to talk; I was reasonably certain that was what she was holding back. And that letter business—”
    â€œDid you really think she wrote that letter?”
    â€œNot for a moment. Except for psychos, murderers don’t admit their killings—even in disguised handwritings—at a time when they’re not even suspected. And Ellen’s Britishness was so blatant that anyone could have used the British dating system to frame her. So although I knew she hadn’t written that threatening letter to herself, I accused her of it last night to frighten her into putting the finger on Thorp.
    â€œThorp, of course, was the one who wrote the letter. He counted on my spotting the Anglicism and pinning it on Ellen for the reason I gave—that double whammy about if-she-wants-us-to-think-she’s-innocent-she-must-be-guilty. And if I hadn’t spotted it, he could always have called it to my attention.
    â€œIt may even be that Thorp originally designed the frame-up letter to be used by him in the event Ellen did talk and accused him of what she’d seen. The trouble was, even when Ellen kept her mouth shut, Thorp had second thoughts. That poisoned chocolate business wasn’t an attempt on Ellen’s part to make herself look innocent, as I mendaciously suggested last night in putting the pressure on her; it was a genuine attempt by Thorp to shut her mouth before she could open it. He expected us—if it had succeeded—to accept it as a suicide-confession.”
    â€œIncidentally,” said the Chief, “you said you knew it was Thorp—”
    â€œA slight exaggeration. I had reason to suspect Thorp, but I had no proof—not an iota; and I was afraid another attack on Ellen might succeed.”
    â€œBut why,” asked the Chief, “would a man like Thorp murder his best friend in cold blood? He’s confessed to the killing, but we haven’t been able to get a word out of him about motive. It certainly can’t be that measly twenty thousand Godfrey was leaving him.”
    Ellery sighed. “The collector breed are a strange lot, Newby. In spite of what he told Godfrey, Thorp probably didn’t consider himself too old to go on that expedition to West Africa; he must have been waiting desperately for years for what he thought was going to be a hundred thousand dollars to finance the trip. When he learned that Godfrey’s carelessness had caused it to shrink to only one-fifth of that, he flipped. That expedition was the dream of his life. Is there anyone we can come to hate more than the loved one who disappoints and frustrates us?”
    Newby held up his hand as Ellery rose. “Wait a minute! What made you suspect Thorp in the first place? It must be something fancy I missed.”
    Ellery did not display pride. His Wrightsville triumphs too often felt like defeats. Perhaps it was because he loved the old town, and it had been his lot to clean up her filth.
    â€œNothing fancy, Newby. The dreariest kind of slip on Thorp’s part. When you and I first went to the house, they told us in detail what had gone on at the discovery of the body. The line of previous action was very clear. Margaret Caswell rushed out of Godfrey’s bedroom, crying out that the old man was—mark the word— dead . They all rushed