"It's something that makes our job easier and it's another tool for the community that makes us a little bit safer," said St. Louis police Lt. Ronald Danback.

He oversees the system in the city's 4th District, which covers downtown and has higher levels of car-related crime than other parts of the city because of the influx of weekday workers, tourists and late-night drinkers.

In St. Louis, Bates and other officers use the license-plate scanning car during normal patrols. The system is constantly working as officers respond to calls. The scanners can capture about 3,600 plates per hour, can be effective in the dark and reportedly can recognize a plate passing at up to 160 mph.

The system also stores the time and GPS coordinates of every plate it photographs, providing police with a useful backtracking tool should the need ever arise.

Once a license plate is scanned into the police database, the computer cross-checks the plate with police records to see if it matches any stolen vehicles, wanted subjects, Amber Alerts, the sex offender registry or any plate manually entered in by officers.