“How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?”
— Arthur Conan Doyle,
The Sign of Four

When the mundane becomes extraordinary, a subtle scent in the air conjures up a familiar face, or a trace of cigarette ash and stub narrows down the suspects like a shrinking Venn diagram, you know that in Sherlock Holmes’ foggy Victorian London, the game is decidedly afoot. Between Edgar Allan Poe’s pioneering of the detective story with The Murders in the Rue Morgue in 1841 and Arthur Conan Doyle’s debut of Sherlock Holmes in A Study in Scarlet in 1887, happenstance and serendipity often dictated the course of crime fiction. Drawing inspiration from Poe, Conan Doyle crafted Holmes partly in the image of Poe’s detective C. Auguste Dupin. However, Doyle elevated Holmes beyond mere intuition, portraying him as a man of science and a trailblazer in forensic methodology. Sir Arthur Ignatius Conan Doyle was born on 22 May 1859 as the second child of Charles Altamont and Mary Foley Doyle in Edinburgh, Scotland (United KIngdom).

He embarked on seven years of Jesuit education in Lancashire, England, in 1868. Following an additional year of schooling in Feldkirch, Austria, he returned to Edinburgh. Influenced by Dr Bryan Charles Waller, his mother’s lodger, Doyle prepared for entry into the University of Edinburgh’s Medical School. He earned his Bachelor of Medicine and Master of Surgery degrees in 1881, followed by an M.D. in 1885. As a medical student, Doyle was profoundly impressed by his professor, Dr Joseph Bell, whose keen observational skills regarding patients’ conditions became the inspiration for Doyle’s literary creation, Sherlock Holmes. Emphasising the importance of meticulous observation, Bell instilled in his students the principle that accurate patient diagnosis hinges upon the astute examination of minute details.

Renowned for his contributions to forensic pathology, Bell was among the earliest experts to collaborate with law enforcement agencies, providing crucial testimony in notable cases such as that of Alfred Monson. In 1893, Monson faced trial for the shooting of his wife’s lover, which he attempted to conceal as a hunting accident, with Bell’s expert insights playing a pivotal role in the judicial proceedings. Holmes first appeared in A Study in Scarlet, embodying the master of diagnostic deduction modelled after Dr Bell. In the above story, Holmes is described as “…well up in anatomy, and … a first-class chemist,” who “has never taken out any systematic medical classes” but has nonetheless “amassed a lot of … knowledge which would astonish his professors.”

In numerous instances, Conan Doyle portrayed Holmes employing methodologies that preceded their adoption by official police forces in both Britain and the USA. That was a time when logic, deduction and scientific principles predominated as methods of detection. Holmes is acknowledged as a spearhead in fingerprint analysis, as evidenced by its first reference in the 1890 novel, The Sign of the Four, over a decade before Scotland Yard’s comprehensive adoption. However, this assertion, while accurate, overlooks the British practice of utilising handprints in Bengal, India, since 1858, as a substitute for local signatures.

Sir William Herschel, a British ICS officer in India, began using fingerprints on native contracts. This was done in order to deter locals from disavowing their signatures on civil contracts. By 1880, fingerprints were starting to be used for identification purposes. Additionally, Holmes utilised footprint analysis as a forensic tool, tracing back to his earliest cases in 1887 and persisting through to The Adventure of the Lion’s Mane (1926). In The Boscombe Valley Mystery, footprint analysis too played a significant role in solving the case. Holmes’ expertise extended across various surfaces, from clay soil to bloodstains, reflecting his comprehensive understanding. His dexterity with footprint analysis was such that he authored a monograph on tracing footsteps, accompanied by insights on the application of plaster of Paris as a preservative of impressions. Sherlock Holmes demonstrated innovative prowess in typewritten document analysis, notably showcased in A Case of Identity (1891). While others overlooked the significance, Holmes astutely observed the absence of handwritten elements in the letters received by Mary Sutherland from Hosmer Angel, a detail leading him to the culprit.

By scrutinising a typewritten note from his suspect, Holmes discerned the unique characteristics of the typewriter, showcasing his acute analytical skills. This predates the establishment of the USA’s Federal Bureau of Investigation’s document analysis section in 1932, once again positioning Holmes at the vanguard of detective methodology. Holmes also exhibited remarkable proficiency in handwriting analysis. With expertise bordering on the forensic, Holmes discerned the gender of an individual and inferred character traits from handwriting samples. He adeptly compared writings to deduce familial relationships and authored a monograph on document dating. Notably, in The Adventure of the Reigate Squire, Holmes identified joint authorship of an incriminating note, swiftly implicating the Cunninghams. In The Adventure of the Norwood Builder, Holmes’ scepticism about a will’s authenticity stemmed from his analysis of the handwriting, portraying his deductive prowess from the case’s inception. Among the array of forensic techniques associated with Holmes, none is more renowned than his use of a magnifying glass, which has become as integral to his iconic image as the deerstalker cap and calabash pipe.

Its initial mention in A Study in Scarlet indeed marks the first instance in fiction where a magnifying glass is employed to scrutinise a crime scene, despite the instrument’s historical presence in various forms for centuries prior. Holmes is frequently acknowledged as the pioneer in recognising the significance of crime scene preservation. Across various narratives, he emphasised the necessity to meticulously document and safeguard all findings at a crime scene, irrespective of their apparent insignificance.

In The Boscombe Valley Mystery, he lamented the contamination of a crime scene by the footprints of a search party, remarking on the missed opportunity for a straightforward investigation had he arrived prior to their intrusion, likening their actions to that of a disruptive herd of buffalo. Holmes also demonstrated adeptness in deciphering a diverse array of ciphers throughout his exploits. Holmes’ most notable feat in cryptology occurred in The Adventure of the Dancing Men, where he employed frequency analysis to decipher stick figure messages, a method reminiscent of Edgar Allan Poe’s use of a similar technique in The Gold Bug.

In The Adventure of the Gloria Scott, he discerned a pattern where only every third word in a message held the intended meaning, a system reminiscent of techniques employed during the American Civil War and echoed in the decryption methods of listeners to the Captain Midnight radio show in the 1940s using their decoders. In The Valley of Fear, Holmes strategically infiltrated Professor James Moriarty’s organisation, employing a book cipher to decode an encoded message, a tactic reminiscent of Benedict Arnold’s espionage tactics during the American Revolutionary War. Holmes can be credited as an early proponent of utilising canine assistance in crime-solving, a facet underscored by Conan Doyle through a number of dog-centric narratives.

The remark delivered by Inspector Gregory in The Adventure of Silver Blaze (1892) —“The dog did nothing in the night-time” – served as a focal clue that elicited bafflement from the characters. In The Sign of the Four, Toby the dog failed to track Tonga (the Pygmy from the Andaman Islands) using the scent of creosote. Again, the dog Pompey in The Adventure of the Missing Three-Quarter adeptly tracked Godfrey Staunton using the distinct smell of aniseed. Conversely, in The Adventure of Shoscombe Old Place (1927), Lady Beatrice Falder’s dog’s uncharacteristic behaviour served as the linchpin for unveiling the mystery. Back in the days of yore, when dogs were still in the process of domestication, they were used by the Romans for security and hunting purposes.

Similarly, Spanish conquistadors harnessed the capabilities of dogs as indispensable assets in warfare, utilising them for scent tracking, scouting, patrolling and messenger duties. In 1888, the English were among the pioneers in utilising police dogs, employing bloodhounds’ exceptional olfactory abilities in the search for the notorious serial killer, Jack the Ripper (who was never found). Subsequently, in 1899, Belgium initiated the formal training process for law enforcement dogs, marking a significant step forward in the professionalisation of K9 units. The persisting legacy of Sherlock Holmes eclipses bare fiction, resonating with the real-world evolution of forensic science.

Sir Arthur Conan Doyle, through Holmes’ pioneering use of forensic methodologies laid the groundwork for modern investigative techniques. As we bid adieu to the smoke-filled rooms of 221B Baker Street, let us not forget the elementary truth: there exists only one consulting detective in the world, and his name is Sherlock Holmes.

(The writer is a journalist on the staff of The Statesman.)