Dr Jakes Bondesio signed a death certificate for heart failure within ten minutes of seeing the body. To be fair to him, oleander does exactly that to a heart. But a doctor who had known the man for forty years, and knew what grows beside the dam, didn't ask a single question. That alone would make you want to look in his pockets.
The Inspector did. In the inside pocket of his dinner jacket she found a heavy silver bookmark engraved E.M., the one missing from the library.
The doctor went very pale and then, to his credit, told the truth. When he examined the body, he saw the bookmark lying on the floor by the chair, where it had fallen. It was solid silver. He owes a great deal of money to people who are not patient. "Eduard would have laughed at me," he said. "He'd have said, take it, Jakes, you'll need it more than me now."
And the certificate? "I wanted it to be his heart. I wanted it to be natural. I didn't want to know what I'd find if I looked properly."
The Inspector checked the doctor's movements. He rang the front doorbell at ten past six, Stefaans showed him straight into the drawing room, and he spent the next fifty minutes there with Jo, the Professor and a martini. He never went near the library, and Bettie, who would know, heard no complaint about it from Joggie.
The Inspector's note: A thief, a coward and a bad doctor. Not, as far as I can see, a murderer.
Meanwhile at Laaste Hoofstuk. Dr Bondesio drove back up the valley on Tuesday to return the silver bookmark to Rentia in person. He apologised for a long time. Rentia listened, turned the bookmark over in her hands, and gave it back to him. "Sell it," she said. "Pay them. And stop, Jakes." He made himself a martini afterwards, out of habit, and then poured it down the sink. Stefaans, who saw it happen, describes it as "a moment of considerable significance".
PS: Dr Watson is a doctor, and so was his creator. Arthur Conan Doyle set up as an eye specialist in London in 1891. By his own account, not a single patient came through the door. He spent the empty hours writing Sherlock Holmes stories, which, all things considered, worked out rather well.