On April 2, 1920, the Police Committee recommended the purchase of equipment for the Bertillon system, rogues gallery, lost and stolen property index and E.M.O. system and M.O. system at a price not exceeding $1,100. The Bertillon method was, at that time, the accepted way of positively identifying a suspect using precise measurements of the skull. It would be several years before this was dropped in favor of exclusive use of fingerprints. Early mug shots contained picture, fingerprint, and Bertillon measurements. A rogue's gallery, stolen property and M.O. files were also set up.Prior to this, information was passed among officers by word-of-mouth.
On July 15, 1921, Police Sergeant Dewey C. Brown was approved for training at the FBI Fingerprint School in Washington, DC. His expenses were paid by the City. The next year the position of "Fingerprint Expert" was added to the Police budget.
Fingerprinting was also done for civil identification.