Pictured: Alphonse Bertillon – Archives of Service Regional d’Identité Judiciaire, Préfecture de Police, Paris via Jebulon on Wikipedia
While the photographing of criminals began in the 1840s shortly after the invention of photography, it was not until 1888 that French police officer Alphonse Bertillon standardised the process.
Mug shots, which were typically taken after a person was arrested, allowed law enforcement to have a photographic record of an arrested individual to allow for identification purposes by victims, the public and investigators.
Alphonse Bertillon (24 April 1853 – 13 February 1914) was a French police officer and biometrics researcher who applied the anthropological technique of anthropometry to law enforcement creating an identification system based on physical measurements.
Anthropometry was the first scientific system used by police to identify criminals.
Before that time, criminals could only be identified by name or photograph. The method was eventually supplanted by fingerprinting.