The Science of Sherlock Holmes: From Baskerville Hall to the Valley of Fear, the Real Forensics Behind the Great Detective's Greatest Cases

by E. J. Wagner

  Sir Sydney observed that in each case, right and left shoes showed wear very differently, and he suspected that the owner had a deformity of his left leg. He had gelatin casts made of the inside of the shoes. Evaluating these carefully, Sir Sydney found that the casts were identical to each other and had been worn by the same individual. Also, “from an examination of his footwear, I was able to build up quite a distinctive picture of the man … he walked with a limp,” the doctor wrote. Although Sir Sydney had never seen the accused burglar until he testified in his case, the elaborate description of spinal curvature and a shortened leg he had constructed proved to be accurate.

  The burglar confessed. His severe deformity had been the result of childhood polio, and his dexterity with drainpipes could only have been the result of grim determination. After his conviction, he agreed to be photographed and x-rayed, and so he made a helpful contribution to the forensic use of footwear.

  But this was an unusual case. Through the early years of the twentieth century, the study of footprints continued to be merely the ill-treated stepchild of medical jurisprudence, and many of the doctors asked to give evidence in the matter did not share Sydney Smith’s interest or creativity.

  Writing at the end of the nineteenth century about the importance of footprint evidence, Hans Gross made the sensible suggestion that footprints should not be primarily the province of physicians, although he agreed that the opinion of “interested” medical men would be useful. He pointed out that an “intelligent shoemaker” could be of great help in matching boot to owner as well, and he insisted that the final responsibility for putting all the evidence together must remain with the investigator of a criminal case. In spite of Dr. Gross’s belief in the usefulness of footprint evidence, the development of footprint comparisons continued to lag behind research in other branches of forensic science. In this discipline, Sherlock Holmes was clearly ahead of his time.

  In the 1940 edition of Modern Criminal Investigation by Söderman and O’Connell, the chapter on footprints states, “Footprints are generally not used sufficiently by investigators of crime. Experience is needed… . [O]nce the eye has become accustomed to observe minute details a composite picture of interesting facts will stand out very clearly.”

  Sherlock Holmes no doubt would have agreed.

  Whatever remains

  • When man landed on the moon for the first time in July 1969, astronaut Neil Armstrong photographed the mark made by a booted human foot on the lunar surface.

  • Footprints are still an important part of criminal investigation, but properly identifying them at a crime scene may be complicated by the footmarks made by first responders. Solutions to this difficulty include plastic bands with identifying marks slipped over shoes, distinctive treads on police shoes, and plastic booties slipped over footwear.

  • A number of law enforcement agencies including the FBI now maintain computerized programs that are designed to match unknown footwear impressions with the brand and manufacturer of the footwear.

  • A Florida medical examiner was able to determine that a drowning death in a submerged vehicle was a suicide because of the firm imprint of the deceased’s foot on the accelerator.

  • Thomas Noguchi, while chief medical examiner for Los Angeles, was puzzled by a bullet wound in the forehead of a corpse. There was no exit wound, and no bullet in the head. He concluded that the wound had been made by a spikeheeled shoe, and a shoe with dried blood on the heel that matched the wound was found nearby.

  CHAPTER 10

  The Real Dirt

  Knowledge of Geology.—Practical, but limited. Tells at a glance different soils from each other. After walks has shown me splashes upon his trouseres, and told me by their colour and consistence in what part of London he had received them.

  —from Dr. Watson’s description of Holmes’s abilities in A Study in Scarlet

  Sherlock holmes is as obsessive about interpreting the subtle marks left on victims or suspects by their habits as he is about the observation of dust and fiber left at crime scenes. “Here, too, is a curious little work upon the influence of a trade upon the form of the hand,” he tells Watson in The Sign of Four, “with lithotypes of the hands of slaters, sailors, cork-cutters, compositors, weavers, and diamond-polishers. That is a matter of great practical interest to the scientific detective—especially in cases of unclaimed bodies, or in discovering the antecedents of criminals.”

  Holmes was absolutely correct. During the very period in which Conan Doyle was constructing the Sherlock Holmes Canon, trace evidence was becoming a vital part of criminalistics.

  Hans Gross, writing in 1893, six years after A Study in Scarlet, stressed the importance of “occupational dust.” “There are,” he wrote, “a surprising number of callings which leave their traces on

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  the clothing and under the fingernails of those who practice them. The clothing of the chimney sweep will contain soot, finely powdered cinders and coal, and possibly traces of mortar.” He discussed the varieties of dust that might be found on the clothes of miners, bricklayers, hairdressers, brewery workers, and pigeon breeders, as well as the importance of fibers, hair, plant life, and even excreta that might be found at a crime scene. The preferred method of gathering such material was first to examine the clothing carefully in a good light with a magnifying glass and to carefully remove visible material and label it. Then the clothing was inserted in a bag, which was shaken or struck vigorously to release any clinging fragments that needed microscopic examination. (In later years, this step was simplified by the use of a vacuum cleaner.)

  In 1904, by which time Dr. Gross’s innovative book had gone through several printings, the importance of its contribution to the field of trace evidence was made overwhelmingly clear. In October of that year, near the town of Wildthal in Germany, the strangled body of a woman was found lying in a bean field. Her hands bore the tiny pinprick marks typical of a person who sews for a livelihood. Her scarf, made of bright red and blue silk, had been tied in a killing twist about her neck. She was quickly identified as Eva Disch, a local seamstress. She had evidently been killed where she lay. Searching the area, the police found only a heavily soiled handkerchief as probable evidence. A few years before, this would have yielded little, but the ideas of Hans Gross had influence in the Freiburg im Breisgau district attorney’s office, which had charge of the case. The office contacted Georg Popp, a chemist who owned a commercial consulting laboratory in Frankfurt. Dr. Popp’s specialty originally had been the analysis of tobacco, ashes, and the residues left in cases of suspected arson. Having been consulted in a few forensic cases that touched on these matters, he had developed an intense interest in police science.

  Now, presented by the police with the stained handkerchief from the bean field crime scene, Dr. Popp peered at it through his microscope. Red and blue silk threads, consistent with the scarf used to strangle Eva Disch, clung to the handkerchief, glued to it by shiny strings of nasal secretion. The mucus also held bits of sand, coal, snuff, and crystals of the mineral known as hornblende.

  The police were suspicious of a Karl Laubach, a former Foreign Legionnaire. He had two different jobs, one at a gasworks and one at a gravel pit, which would have exposed him to the varied substances found on the handkerchief. Laubach was also known as a habitual user of snuff.

  As Sherlock Holmes would advise in “The Adventure of the Creeping Man,” “Always look at the hands first, Watson. Then cuffs, trouser-knees, and boots.” Popp scraped under Laubach’s fingernails, examined the gleanings under the microscope, and was richly rewarded. He found coal dust, sand, and crystals of hornblende. He found bits of red and blue fiber that corresponded with fiber from the murder scarf. The trousers of the suspect provided additional encouragement. Loam, bits of crushed mica coal particles, and traces of vegetation clung to the garment, and were consistent with the soil at the scene of the crime. Similar traces were found on a path leading from the crime scene to Laubach’s ho
me. Laubach resisted at first but eventually succumbed to science and confessed.

  Georg Popp continued to wield his microscope in the interest of the law and helped to establish Germany’s place as a primary developer of forensic analysis. He influenced many scientists of the next generation, including the Swedish Harry Söderman. Söderman tells us in his memoir, Policeman’s Lot, that in spite of Popp’s contributions to Germany’s prestige, he and his wife spent their last years secluded in a Black Forest hunting lodge, loathing the Nazi government, and bitter at the struggle they were forced to endure in order to save the life of their Jewish daughter-in-law. Georg Popp died just before the start of the Second World War.

  While Popp was establishing the forensic usefulness of chemistry and the natural sciences in Germany, Edmond Locard, head of the forensic laboratory in Lyon, France, was pursuing similar ideas. Dr. Locard, like Sherlock Holmes, was a man of wideranging interests, and, like Holmes, he had a passion for music. Even while he was developing the forensic laboratory, Locard served as music and theater critic for the Lyon newspaper. (It was said that his office was visited more frequently by apprehensive actors than it was by criminal suspects.) His eclectic interests led him to consider the forensic application of a variety of materials and techniques. He maintained a collection of soil, mineral, fiber, and animal hair samples in the hopes of simplifying the identification of trace evidence recovered at crime scenes.

  Every crevice and fissure in the human body was considered a possible hiding place for trace evidence. Ear wax was of special interest, as small particles of dust will adhere to it even in the face of stringent hygiene. The ears of suspects were often swabbed and the results placed on a slide for examination under a microscope. If pertinent debris was observed, microchemical analysis could be performed. In Locard’s view, “The microscopic debris that covers our clothing and bodies are the mute witnesses, sure and faithful, of all our movements and all our encounters.”

  In 1912, the practicality of this approach became evident when Marie Latelle, a young citizen of Lyon, was found dead of unknown causes in her parents’ home. From the state of rigor, it was clear she had died before the previous midnight.

  Her suitor, Emile Gourbin, a clerk at a local bank, was questioned, but he had a firm alibi: he had been miles away with several friends playing cards until after one in the morning. The friends, who gave every appearance of telling the truth, confirmed his account.

  Dr. Locard was asked to consult. Examining the corpse, he found clear marks of strangulation on the neck. He then examined Gourbin, carefully scraping under the young man’s fingernails and taking the results to his laboratory, where he subjected them to the sort of microscopic examination Holmes performed in “The Adventure of Shoscombe Old Place”:

  Sherlock Holmes had been bending for a long time over a low-power microscope. Now he straightened himself up and looked round at me in triumph.

  “It is glue, Watson,” said he. “Unquestionably it is glue. Have a look at these scattered objects in the field!”

  I stooped to the eyepiece and focused for my vision.

  “Those hairs are threads from a tweed coat. The irregular gray masses are dust. There are epithelial scales on the left. Those brown blobs in the centre are undoubtedly glue.”

  Locard had similar good fortune. Peering through his microscope, he discovered tiny flakes of epithelial cells, which might have come from the victim’s neck. This was not certain, as they might instead have come from Gourbin. There was, however, an unusual pink dust that clung to the skin cells. Locard found the pink dust to contain magnesium stearate, zinc oxide, and iron oxide pigment, also known as Venetian red. Traces of rice powder were also present in the sample. The sophisticated, theater-loving Locard believed that the pink dust was a cosmetic.

  Facial makeup had been variously acceptable and unacceptable in Europe for centuries. In the eighteenth century, even men had worn it. During the early Victorian period, makeup had been used discreetly by ladies, but after 1890, it was considered both racy and passé among “nice” women, although tiny dustings of white starch were allowed to produce an “interesting” fashionable pallor.

  Ladies made do by using burned matches to darken lashes, flower petals to stain lips, and occasionally arsenic-laden flypaper to improve their complexions. At the turn of the twentieth century, the purchase of makeup was a surreptitious undertaking.

  By 1910, things had begun to change. Sergei Diaghilev’s Ballets Russes had created a sensation in Europe, and the dramatic makeup used by the dancers influenced fashion. Middle-class women began to experiment with creams, powders, and even mascara. But as these fripperies were not yet mass produced, the source of a cosmetic was important evidence.

  A diligent search in Lyon located the chemist who had custommade Marie Latelle’s powder. Confronted with this information, Gourbin confessed. He had constructed his alibi by setting the clock ahead an hour and a half so that it appeared he was with his friends at the time of the killing. His friends, glowing with wine and gambling with cards, had not noticed. Gourbin’s trick of playing with time provided the prosecution with convenient evidence of premeditated murder.

  Edmond Locard’s reputation and that of his laboratory were burnished by the Latelle case and attracted both students and research funds to Lyon. Locard wrote a classic seven-volume study of forensic science, Traité de criminalistique, which would influence generations of scientists. He stated, “Il est impossible au malfaiteur d’agir avec l’intensité que suppose l’action criminelle sans laisser des traces de son passage” (It is impossible for a criminal to act, considering the intensity of a crime, without leaving a trace), and so he became known among forensic scientists as the originator of Locard’s Exchange Principle, which states that every contact leaves a trace. Although Locard evidently never phrased his idea in just that way, it is implicit in the underlying philosophy of his work, just as it is in Sherlock Holmes’s remark in “The Adventure of Black Peter,” “As long as the criminal remains upon two legs so long must there be some indentation, some abrasion, some trifling displacement which can be detected by the scientific searcher.”

  In 1949, a case that began in the genteel environs of the Onslow Court Hotel in South Kensington, London, provided an interesting example of the exchange principle as well as the value of basic geology in forensic detection. The hotel was home to a number of very respectable retired people, among them Mrs. Henrietta Helen Olivia Roberts DurandDeacon, a sixty-nineyear-old widow. Although Mrs. DurandDeacon was financially comfortable, she entertained both enterprising ambition and an idea for the manufacture of artificial fingernails. Being a friendly sort, she shared her thoughts with a fellow resident, the fortyyear-old, dapper John George Haigh. Mr. Haigh listened attentively and then suggested that Mrs. DurandDeacon visit a factory he owned in Crawley, West Sussex, to see if those premises might be appropriate for the production of cosmetic nails. She accepted, and the date for this venture was set for February 18.

  Two days later, during breakfast at the Onslow Court Hotel, Haigh expressed his concern about Mrs. DurandDeacon’s whereabouts to other guests. He explained that he had arranged to meet the lady at the Army Navy store where she had an errand and planned to drive her to his factory from there, but she had not kept the appointment. The other guests were alarmed, and a decision was made to contact the police.

  A female officer, Police Sergeant Lambourne, interviewed Haigh. His unctuous manner made her uneasy at once, and she industriously checked police records to see if his name appeared. It did. He had served time for fraud and theft repeatedly in Nottingham, Surrey, as well as in London. Perhaps Mrs. DurandDeacon’s friendly trust in Haigh had been unwise.

  The now highly suspicious police visited Haigh’s factory on Leopold Road in Sussex and discovered that it was little more than a storeroom. The storeroom did contain a few objects of interest: a .38 Enfield revolver, eight rounds of the appropriate ammunition, some rubber protective clothing, a d
ry-cleaning receipt dated February 19 for a Persian lamb coat much like one owned by Mrs. DurandDeacon, and three carboys (special containers for corrosive liquids) of sulfuric acid.

  A few days after the examination of the “factory,” the jewels that the missing lady had been wearing turned up in a shop, which had purchased them for one hundred pounds. Mr. Haigh was invited to “help the police with their inquiries.”

  At an interview with Detective Inspector Webb on February 28, Haigh suddenly leaned forward and said, “Tell me frankly. What are the chances of anyone being released from Broadmoor [an institution for the criminally insane]?”

  Webb didn’t respond. Haigh then told him that the truth was too fantastic for belief. Webb delivered the formal caution, and Haigh responded, “Mrs. DurandDeacon no longer exists. She has disappeared completely, and no trace of her can ever be found again. I have destroyed her with acid. You will find the sludge which remains on Leopold Road. But,” he said, smiling confidently, “you can’t prove murder without a body.”

  Mr. Haigh was mistaken on this point, as many others have been. The law does not require a corpse to prove murder; it requires a corpus delicti—the body of evidence that establishes that the crime has taken place. Haigh, not understanding this, his ego racing at full gallop, proceeded to dictate a complex confession. He had killed Mrs. DurandDeacon and at least five other people over the years, but he had a very good reason for his bad behavior.

  He was, he explained, a vampire, and was in dire need of their blood. He had shot Mrs. DurandDeacon in the back of the head at the storeroom at Crawley, then made an incision in the side of her neck, collected a glass of blood, and drank it. Removing her fur coat and jewels, he then put her clothed body into a vat, poured acid over it, and went to tea, at which meal he ate a poached egg. Returning to his labors, he refilled the vat with acid a number of times over the next few days and then, judging his project complete, emptied the vat into the street. He had used the same methods on his other victims, all of whom, he happily reported, were also beyond recovery.