IT WAS ONE OF THE MOST NOTORIOUS MURDERS OF ITS age. Galvanizing early twentieth-century Britain and before long the world, it involved a patrician victim, stolen diamonds, a transatlantic manhunt, and a cunning maidservant who knew far more than she could ever be persuaded to tell. It was, Sir Arthur Conan Doyle wrote in 1912, “as brutal and callous a crime as has ever been recorded in those black annals in which the criminologist finds the materials for his study.”
But for all its dark drama, and for all the thousands of words Conan Doyle would write about it, the narrative of this murder was no work of fiction. It concerned an actual case: a killing for which an innocent man was pursued, tried, convicted, and nearly hanged. It would also consume him—as private investigator, public crusader, and ardent nonfiction chronicler—for the last two decades of his life.
The case, which has been called the Scottish Dreyfus affair, centered on the murder of a wealthy woman in Glasgow just before Christmas 1908. The next spring, Oscar Slater, a German Jewish gambler recently arrived in the city, was tried and condemned for the crime. His very name became so notorious that for years afterward the phrase “See you Oscar” was Glasgow rhyming slang for “See you later”—as in “See you later, Oscar Slater.”
By the time he cast his lot with Oscar Slater, Conan Doyle had been intimately involved in righting another notorious wrongful conviction, that of George Edalji, a young Anglo-Indian lawyer imprisoned in 1903 for maiming livestock. Conan Doyle’s personal investigation of that case, is the subject of a spate of nonfiction books and also inspired Arthur & George, Julian Barnes’s acclaimed novel of 2005.
But the Slater case, though it involves homicide, remains less well known, perhaps because it is more troubling than any other Conan Doyle tackled. Yet the case was Conan Doyle’s last stand as a true-crime investigator, and a remarkable stand it was. The story of his long effort to free Slater throws into relief the singular temperament that let Conan Doyle light the age in which he lived: his passion for righting wrongs, his willingness to wade headlong into battle, a sense of honor so intense that it trumped personal antipathies, and a talent for rational investigation that far outstripped that of the police. Where today many wrongful convictions, some decades old, have been overturned with the help of DNA analysis, Conan Doyle managed to free Slater by virtue of little more than minute observation and rigorous logic—precisely the kind of brainwork that had made his hero world famous.
Besides being the true-crime narrative of the exoneration of a wrongly condemned man in the age before modern forensics, Conan Doyle for the Defense is also a study of the singular method of detection that Conan Doyle used to such magnificent effect in the Holmes stories, here applied by him to an actual murder. As the book explains, it was no accident that the man who saved Slater was both crime writer and doctor, for at their core, detection and doctoring are similarly rooted in the art of diagnosis. This exquisite art, which hinges on the identification, discrimination and interpretation of barely discernible clues in order to reconstruct an unseen past (a skill that Holmes memorably described as the ability to “reason backward”), animates Conan Doyle’s approach to nearly every aspect of the case.
In his published accounts of the case and his archived letters on the subject, Conan Doyle reveals a modus operandi that can truly be called Holmesian. His method entailed the search for small details whose significance other investigators had missed, the picking apart of logical inconsistencies in the behavior of police and prosecutors, an eye for negative evidence and the keen understanding of its value and, as Holmes would have said, the ability to observe rather than merely to see. All this he would use to loosen, link by link, the chain of circumstantial evidence that had been forcibly tightened round Slater’s neck.
CONAN DOYLE FOR THE DEFENSE: A Sensational Murder, the Quest for Justice and the World’s Greatest Detective Writer by Margalit Fox is published by Profile, £16.99