Osvaldo Ruiz and a friend were hiking through an isolated stretch of mountains, just a few miles from the sprawling US-Mexico border wall that fringes San Diego, when the federal agent stopped them in their tracks.
It was late March, mid-morning, and Ruiz, who works for a local non-profit called Border Angels, was busy. That day he was scouting a new route where his group could leave life-saving water and food for the sporadic waves of migrants who still cross through these desolate borderlands. Ruiz and his friend, a fellow Border Angels member, already knew they were being watched. A helicopter had been buzzing overhead for the past several hours, tracking them.
