CSI:Time Machine

Before fingerprinting

It was essentially a criminal justice Dewey Decimal System, the first step in taking police out of the dark ages. Before Bertillion standardized measurements, police just had a jumble of descriptions and photographs with no way to organize them so they’d almost never be able to cross reference existing records when people were arrested.

Fingerprinting isn’t the only technology difference in criminal investigation, of course. Much of forensic pathology dates from after this time.