Isn't this just wonderful.
The Hennepin County Sheriff's Office and Bureau of Criminal Apprehension have both purchased cellular exploitation devices that go by the names of KingFish of StingRay. The devices mimic a cell phone tower and allow the agencies to extract data from nearby cell phones.
http://archive.kare11.com/rss/article/1048249/391/Minnesota-law-enforcement-tracking-cell-phones