Eider'The company is called Fog Data Science, and its product uses location data harvested from smartphones either through ordinary apps or the advertising ecosystem. In 2022 the Electronic Frontier Foundation (EFF) revealed Fog had sold its phone tracking technology to multiple U.S. agencies, including local police.'
https://www.404media.co/location-data-firm-offers-to-help-cops-track-targets-via-doctor-visits/
Location Data Firm Offers to Help Cops Track Targets via Doctor Visits
Fog Data Science is a location tracking company that takes data harvested from smartphones and makes it accessible to cops. A document obtained by 404 Media shows the company explicitly says it will use doctors visits to unmask a target if needed.