John Longan was an agent with the US Border Patrol in the 1940s and '50s. Following the 1959 Cuban Revolution, Longan ... moved on to work for the CIA. Put simply, Longan taught local intelligence and police agencies how to create death squads to target political activists, deploying tactics that he'd used earlier to capture migrants on the border. He arrived in Guatemala in late 1965 and put into place a paramilitary unit that, early the next year, would execute what he called Operación Limpieza, or Operation Cleanup. Within three months, this unit conducted over 80 raids and multiple assassinations, including an action that, over the course of four days, led to the capture, torture, and execution of more than 30 prominent left-wing opposition leaders. The military dumped their bodies into the sea, while the government denied any knowledge of their whereabouts. Longan's Operación Limpieza was a decisive step in the unraveling of Guatemala, empowering an intelligence system that over the course of the country's civil war would be responsible for tens of thousands of disappearances, 200,000 deaths, and countless tortures. It was common practice during the Cold War to send former Border Patrol agents to train foreign police through CIA-linked "public safety" programs. Men like Longan helped speed up the pace with which local security forces could target and kill political reformers, thus accelerating political polarization and social misery.