How police work with Google to obtain cellphone location data for criminal investigations

With help from Google, police can drop a virtual dragnet over crime scenes that locate people’s phones within about 10 feet of accuracy. A warrant launches a three-step process, which starts with the tech giant providing anonymous information and can progress to include names and emails connected to a subset of targeted phones.

The practice raises concerns about invasion of privacy and questions about whether geofence results actually solve crimes. Details of how police and tech companies work together, and how rigorous the courts are before issuing warrants, remain scant.