This week on Fronteras: We continue our conversation with Francisco Cantú, former Border Patrol agent and author of “The Line Becomes a River: Dispatches from the Border.” The book recounts Cantú’s time patrolling the deserts of Arizona, New Mexico and Texas, where he encountered drug smugglers, as well as immigrants looking for better lives in the U.S. In part two of our interview: Cantu recounts his time living and working in El Paso. The stresses of the job are revealed in nightmares (3:07 ).