https://www.vice.com/en_us/article/epdpdm/ice-dhs-fbi-location-data-venntel-apps

Venntel, a government contractor that sells location data of smartphones to U.S. law enforcement agencies including ICE, CBP, and the FBI, gathers information through a highly complex supply chain of advertising firms, data resellers, and ultimately innocuous-looking apps installed on peoples' phones around the world, according to a cache of documents obtained by Norwegian media organization NRK and shared with Motherboard.

Although it's not clear if Venntel ultimately provides all data generated from this specific supply chain to agencies such as ICE, the documents provide much deeper and previously unreported insight into how data moves from apps, middlemen companies, and through to data brokers. In this case, Venntel.