Was the death of Richard Lancelyn Green, the world’s foremost Sherlock Holmes expert, an elaborate suicide or a murder? Illustration by Jean-François Martin

Richard Lancelyn Green, the world’s foremost expert on Sherlock Holmes, believed that he had finally solved the case of the missing papers. Over the past two decades, he had been looking for a trove of letters, diary entries, and manuscripts written by Sir Arthur Conan Doyle, the creator of Holmes. The archive was estimated to be worth nearly four million dollars, and was said by some to carry a deadly curse, like the one in the most famous Holmes story “The Hound of the Baskervilles.”

The papers had disappeared after Conan Doyle died, in 1930, and without them no one had been able to write a definitive biography—a task that Green was determined to complete. Many scholars feared that the archive had been discarded or destroyed; as the London Times noted earlier this year, its whereabouts had become “a mystery as tantalizing as any to unfold at 221B Baker Street,” the fictional den of Holmes and his fellow-sleuth, Dr. Watson.

Not long after Green launched his investigation, he discovered that one of Conan Doyle’s five children, Adrian, had, with the other heirs’ agreement, stashed the papers in a locked room of a château that he owned in Switzerland. Green then learned that Adrian had spirited some of the papers out of the château without his siblings’ knowledge, hoping to sell them to collectors. In the midst of this scheme, he died of a heart attack—giving rise to the legend of the curse. After Adrian’s death, the papers apparently vanished. And whenever Green tried to probe further he found himself caught in an impenetrable web of heirs—including a self-styled Russian princess—who seemed to have deceived and double-crossed each other in their efforts to control the archive.

For years, Green continued to sort through evidence and interview relatives, until one day the muddled trail led to London—and the doorstep of Jean Conan Doyle, the youngest of the author’s children. Tall and elegant, with silver hair, she was an imposing woman in her late sixties. (“Something very strong and forceful seems to be at the back of that wee body,” her father had written of Jean when she was five. “Her will is tremendous.”) Whereas her brother Adrian had been kicked out of the British Navy for insubordination, and her elder brother Denis was a playboy who had sat out the Second World War in America, she had become an officer in the Royal Air Force, and was honored, in 1963, as a Dame Commander of the Order of the British Empire.

She invited Green into her flat, where a portrait of her father, with his walrus mustache, hung near the fireplace. Green had almost as great an interest in her father as she did, and she began sharing her memories, as well as family photographs. She asked him to return, and one day, Green later told friends, she showed him some boxes that had been stored in a London solicitor’s office. Peering inside them, he said, he had glimpsed part of the archive. Dame Jean informed him that, because of an ongoing family dispute, she couldn’t yet allow him to read the papers, but she said that she intended to bequeath nearly all of them to the British Library, so that scholars could finally examine them. After she died, in 1997, Green eagerly awaited their transfer—but nothing happened.

Then, last March, Green opened the London Sunday Times and was shocked to read that the lost archive had “turned up” at Christie’s auction house and was to be sold, in May, for millions of dollars by three of Conan Doyle’s distant relatives; instead of going to the British Library, the contents would be scattered among private collectors around the world, who might keep them inaccessible to scholars. Green was sure that a mistake had been made, and hurried to Christie’s to inspect the materials. Upon his return, he told friends that he was certain that many of the papers were the same as those he had uncovered. What’s more, he alleged, they had been stolen—and he had proof.

Over the next few days, he approached members of the Sherlock Holmes Society of London, one of hundreds of fan clubs devoted to the detective. (Green had once been chairman.) He alerted other so-called Sherlockians, including various American members of the Baker Street Irregulars, an invitation-only group that was founded in 1934 and named after the street urchins Holmes regularly employed to ferret out information. Green also contacted the more orthodox scholars of Conan Doyle, or Doyleans, about the sale. (Unlike Green, who moved between the two camps, many Doyleans distanced themselves from the Sherlockians, who often treated Holmes as if he were a real detective and refused to mention Conan Doyle by name.)

Green shared with these scholars what he knew about the archive’s provenance, revealing what he considered the most damning piece of evidence: a copy of Dame Jean’s will, which stated, “I give to The British Library all . . . my late father’s original papers, personal manuscripts, diaries, engagement books, and writings.” Determined to block the auction, the makeshift group of amateur sleuths presented its case to Members of Parliament. Toward the end of the month, as the group’s campaign intensified and its objections appeared in the press, Green hinted to his sister, Priscilla West, that someone was threatening him. Later, he sent her a cryptic note containing three phone numbers and the message “PLEASE KEEP THESE NUMBERS SAFE.” He also called a reporter from the London Times, warning that “something” might happen to him.

On the night of Friday, March 26th, he had dinner with a longtime friend, Lawrence Keen, who later said that Green had confided in him that “an American was trying to bring him down.” After the two men left the restaurant, Green told Keen that they were being followed, and pointed to a car behind them.

The same evening, Priscilla West phoned her brother, and got his answering machine. She called repeatedly the next morning, but he still didn’t pick up. Alarmed, she went to his house and knocked on the door; there was no response. After several more attempts, she called the police, who came and broke open the entrance. Downstairs, the police found the body of Green lying on his bed, surrounded by Sherlock Holmes books and posters, with a cord wrapped around his neck. He had been garroted.

“I will lay out the whole case for you,” John Gibson, one of Green’s closest friends, told me when I phoned him shortly after learning of Green’s death. Gibson had written several books with Green, including “My Evening with Sherlock Holmes,” a 1981 collection of parodies and pastiches of the detective stories. With a slight stammer, Gibson said of his friend’s death, “It’s a complete and utter mystery.”

Not long after, I travelled to Great Bookham, a village thirty miles south of London, where Gibson lives. He was waiting for me when I stepped off the train. He was tall and rail-thin, and everything about him—narrow shoulders, long face, unruly gray hair—seemed to slouch forward, as if he were supported by an invisible cane. “I have a file for you,” he said, as we drove off in his car. “As you’ll see, there are plenty of clues and not a lot of answers.”