Erick Coser found himself at gunpoint. It was March 2024, and he was standing at the door of his girlfriend’s São Paulo apartment building when an unmasked man arrived by food delivery bike. He pulled out a pistol and demanded Coser’s phone and the six-digit code protecting it. Share the wrong combination, the attacker warned, and he’d pull the trigger. Using Find My iPhone, Coser watched the device weave through the suburbs and into a drug cartel-controlled favela on the city's outskirts.