Penlink’s Webloc is an application that locates people using information from the weather, gaming, email, and religious apps on their phone. It’s sold to the police.

The tool collects vast quantities of location data from smartphones via commonly used weather, gaming, email and religious apps. It can build a detailed picture of where a smartphone has been over the past 12 months, and update the data hourly, showing the movements of people on a near real-time basis. Law enforcement officers can use Webloc to zero in on a map and look at all phones that were present at a specific place and time, analyzing “billions of location data points,” according to company documents reviewed by Bloomberg.

There’s a nice infographic that explains how the system works at the link.