BOGOTÁ, Colombia – Mexico has been rocked by a wave of retaliatory violence after authorities killed the leader of the Jalisco New Generation Cartel (CJNG), Nemesio Oseguera Cervantes, alias ‘El Mencho’, last Sunday. The true impact of his death is yet to be seen, however. The drug kingpin’s killing threatens to unleash a wave of unforeseen consequences in the region’s complex, interconnected criminal underworld beyond Mexico’s borders. The CJNG is one of the most powerful and ruthless criminal organizations in the world, overseeing a vast empire of fentanyl, methamphetamine and...