Originally Posted by Angry Jew Cat

Yup, systems such as this are already in place. West Edmonton Mall's latest security system tracks every individual moving object in the building, and determines based upon your movements whether or not you are a suspicious individual. If the system determines that your movements and activities in the mall are suspicious, it will focus in on you and snap shots until it has a good clear shot of your face, which is then saved to the database. The system then runs your face against the existing database to see if you have been previously identified as a suspicious individual in the building. If your face is a hit in the existing database, security is notified and you are put under manned surveillance.

That system went into effect a few years ago now. But I remember reading about it clearly as the ability of the system blew my mind.