If Joaquín Guzmán Loera, the drug kingpin known as El Chapo, is extradited to the United States, he might face two formidable witnesses: identical twin brothers, former drug traffickers on a major scale, who gathered evidence against him for government prosecutors. Jack Handey tells some “Tales of Old Santa Fe,” where the cowboy past collides with the New Age present. And David Remnick talks with Alicia Garza, who co-founded Black Lives Matter, about the movement’s goals, and her issues with Hillary Clinton.