Two technologies that are coming into greater use in the field of criminal justice are GPS tracking devices and unmanned aerial "drones." Both of these are the subject of some controversy.
Both drones and GPS hold out the possibility of being extremely useful to police. A GPS tracker planted on a car can show where that car has been over a period of time. In addition, the GPS devices that are built into cars can do this tracking for the police, as seen here. Drones can give police a much easier way to search a given area or to follow a car, for example. They can stay up for long periods of time and are relatively cheap to operate.
Both of these, then, are new technologies that appear to have significant applications in the field of criminal justice.