Other personal characteristics change - fingerprints do not. In earlier civilizations, branding and even maiming were used to mark the criminal for what he was. The thief was deprived of the hand which committed the thievery. The Romans employed the tattoo needle to identify and prevent desertion of mercenary soldiers. Photography lessened the burden on memory but was not the answer to the criminal identification problem.
Personal appearances change.
Around 1870 a French anthropologist devised a system to measure and record the dimensions of certain bony parts of the body. This Bertillon System, named after its inventor, Alphonse Bertillon, was generally accepted for thirty years. But it never recovered from the events of 1903, when a man named Will West was sentenced to the U.S. Penitentiary at Leavenworth, Kansas. You see, there was already a prisoner at the penitentiary at the time, whose Bertillon measurements were nearly exact, and his name was William West. Upon an investigation, there were indeed two men.