The Metropolitan Police was founded in 1829. From the beginning, its operations were based on ‘uniform patrol of regular beats in full and open public view’ to assuage concerns that any centrally controlled police form would become a state spying apparatus. The introduction of plain-clothes detectives into the force was therefore slow. It was not until 1869 that each division of the Metropolitan Police got its own detectives, and a centralised Criminal Investigation Department (CID) wasn’t formed until 1878.
Once detectives were established as a permanent part of the police force, leaders at the Metropolitan Police and its counterparts across the country and Empire were keen to ensure consistency of practice. To that effect, in 1906 the Crown and Public Prosecutor in Madras published the first English translation of a work by the Austrian Hans Gross. Handbuch für Untersuchungsrichter als System der Kriminalistik, or Criminal Investigation: A Practical Textbook as it became known in England was originally aimed at lawmakers and police officers in colonial areas. A revised edition was published in 1924, and a third edition appeared in 1934. This third edition was edited by Norman Kendal, then Assistant Commissioner for Crime in the Metropolitan Police.
The work, aiming to be ‘a practical textbook of instruction for all engaged in investigating crime’, runs to 569 pages. Although police detectives tended to have been slightly better educated than patrolling constables, it seems unlikely that they all read and memorised the detailed instructions of Criminal Investigation. Moreover, the book provided instructions on best practice, but most of its contents were not legally binding. In short, the book likely tells us more about the ideal of police investigation than of its day-to-day reality. Nonetheless, it helps us understand how interwar police officers, magistrates and prosecutors understood crime.
During the interwar period, the police did not just investigate a crime up to the point of charging an individual, but were also responsible for collating evidence for the police courts. This often involved working with experts. No wonder then that nearly 100 pages in the book set out ‘The Expert and how to make use of him (sic)’. Specific items include ‘preservation of parts of a corpse’ and ‘colour-blindness’ (‘more widespread and more important than generally believed’). The section on fingerprints was extensively re-written for the third edition, this area of work ‘having advanced by leaps and bounds even since 1924.’
Beyond the practicalities of running a sound investigation, Criminal Investigation also sets out in detail supposedly common practices of various types of criminal. ‘Wandering Tribes’ receive a chapter all of their own, marking Gypsies and Travellers as particularly likely to engage in criminal behaviour – although it debunks the myth that Gypsies steal children (‘It must also be remembered that gipsies (sic) are very prolific and in consequence have no need to bring up other people’s children’).
Criminals ‘shamming’ various afflictions such as blindness, deafness or even epilepsy was apparently a regular enough occurrence to warrant inclusion here, as were criminal superstitions. The reader is told how fortune tellers who claim to have ‘discovered’ the guilty party through divination, tarot cards, or their intuition can derail an investigation. Women in particular are claimed to put investigators on the wrong foot with their ‘presentiments’. There is no practical advice on how to handle such a situation as an investigator other than, presumably, to roundly ignore any tips received through paranormal means.
The third section of the book deals with the skills investigating officers must possess, such as drawing and modelling of crime scenes; observing footprints; and finding traces of blood. Again there is a suggestion that criminals have their own communal language in a chapter on ciphers, which is given in addition to a short list of criminal slang.
The final section of the book categorises particular offences, including ‘Bodily Injuries and Poisoning’; ‘Theft’; ‘Cheating and Fraud’; ‘Arson’ and ‘Serious Accidents and Boiler Explosions’ (split up between ‘False Theories’ and ‘Admissible Theories’). Murder is not included as a category, as murderers were believed to mostly be ‘crimes of impulse’ and very few serial killers were known (Jack the Ripper being an obvious exception). When speaking of ‘criminals’, police inspectors tended to mean those who were repeat offenders, often sticking to the same type of crime such as burglary.
Criminal Investigation was from the outset designed to be used across the British Empire. However, its origins as a Western European text does make one wonder its usefulness for lawmakers and detectives in, for example, India. There is little to no consideration of cultural differences. The impression created is that criminals, like lawmakers, are a homogenous group who behave the same regardless of their physical location or background. This demonstrates how handbooks like Criminal Investigation fostered the consolidation of the British Empire through their discourse.
 Robert Reiner, The Politics of the Police, 3rd edition (Oxford: Oxford University Press, 2000) p. 56
 Haia Shpayer‐Makov, ‘Becoming a Police Detective in Victorian and Edwardian London’, Policing and Society, 14:3, (2004) 250-268, (pp. 251-253)
 John Adam and J Collyer Adam, Criminal Investigation: A Practical Textbook, 3rd edition, edited by Norman Kendal (London: Sweet & Maxwell, 1934), p. xii
 Ibid., p. xiv
 Shpayer-Makov, ‘Becoming a Police Detective’, p. 263
 Adam and Adam, Criminal Investigation, p. 125
 Ibid., p. xii
 Ibid., p. 248
 Ibid., p. 262
 Frederick Porter Wensley, Forty Years of Scotland Yard (New York: Greenwood Press, 1968 ), p. 86