For four years, Francisco Cantú kept watch over the deserts of New Mexico, Arizona and Texas working for the U.S. Border Patrol. He joins guest host Courtney Collins to talk about how his time spent along the border forced him to consider the violence inflicted on those who live along it. His new book is called “The Line Becomes a River: Dispatches from the Border” (Riverhead Books). He speaks tonight at Interabang Books in Dallas. And he’ll be back in Dallas April 8 for an appearance at the Dallas Museum of Art.