A few years ago, during a visit to Colombia, I wanted to photograph a prison, and I wound up at Valledupar, a state-of-the-art facility, designed and paid for by the United States. During my visit I met the prison’s most notorious inmate, a man known by the alias Popeye, who had spent much of his working life as the “head of security” for Pablo Escobar, the godfather of the Medellín cocaine smuggling cartel.