When people think of police mug shots, they remember old movies where a witness or victim is handed a huge book of photos of arrested criminals and spend hours poring over it looking for a bad guys face. While that kind of approach to identifying criminals may have been popular thirty years ago or more, the science of creating and using criminal mug shots has changed greatly in the digital age.
Todays mug shot is taken with a digital camera, which allows it to be used for a number of purposes. In many jurisdictions, police officers in squad cars can access enormous databases full of the photos of arrested criminals and pull them up instantly on a squad car computer to confirm or deny a detainees identity. These photos can also be sent instantly from one department to another, which speeds up the process of sharing photos of wanted criminals between police agencies immensely. This technology also allows non-police photos to be entered into databases and photo lineups by enabling an investigator to change the background of a photo such as a drivers license so that it resembles a standard mug shot and can be used to identify people with no previous arrest photos on record.
Police are also beginning to explore the potential of biometrics, which is in its simplest form the use of measurements and calculation to create a unique numerical profile of a criminals physical characteristics. Facial recognition software can make precise measurements of a criminals facial features such as the distance between the chin and nose tip and then convert that into a numerical score. This can then be compared to another image so that investigators can determine if the photo of an unknown suspect corresponds to a photo of a known criminal on file.
Modern police photo lineups are far different from those of the past. Most jurisdictions have rules regarding the number of photos required in a lineup, and the subjects in the pictures cannot be drastically different so as to make one stand out. A computer program can take a subjects description and automatically generate a lineup of subjects that bear a fair resemblance, which makes the lineup fairer and less likely to influence a victim or witness. For more objectivity, some jurisdictions do not allow the detective who created the lineup to show it to a witness, thus preventing any attempt to influence the identification.
Technology continues to change the way police fight crime on our streets. Police mug shots have come a long way from the days of a victim viewing the usual suspects in a musty old police detective office.