Stingrays won't be able to give exact location but can determine who's cellphone is in the surrounding area and the signal strength of that phone. If you know w

Stingrays won't be able to give exact location but can determine who's cellphone is in the surrounding area and the signal strength of that phone. If you know who that IMSI belongs to, you could setup the Stingray to alert when the IMSI is near. Then you can drive around checking signal strength and send out an officer with a portable unit to literally go door to door checking for where the signal is strongest. Is it legal? Who knows. Cops can drive around with license plate readers automatically looking for certain plates or just cataloging them. Is a nearby phone being tricked into broadcasting it's IMSI similar to recording a publicly visible license plate? That's for the courts to decide. Cops can do parallel reconstruction where they set aside illegally obtained evidence and build up a new chain of legal investigation that arrives at the same conclusion. I suspect that cops aren't willing to gamble on their Stingray-obtained evidence being constitutional so the easiest route is just to use it as a guiding hand for their official, legal investigation and just never make it part of the evidence so it can't really be challenged.