A new surveillance camera system can track movements in a city center for over six hours. Made by the aptly named "Persistent Surveillance Systems," the HAWKEYE II can watch a 4-mile square, and because it goes on the bottom of a manned airplane like a Cessna, it is, unlike drones, probably legal

Researchers at MIT were able to identify people from just four location points generated by their cell phones over the course of a day with 95 percent accuracy. A map that captures movement in real time over a large area could capture similar information, watching the places a person goes after he flees the scene of a crime