The Mexican army killed the country's most powerful cartel leader and one of the United States' most wanted fugitives on Sunday, notching a major victory while cartel members responded with a wave violence across the country. The killing of Jalisco New Generation Cartel leader Nemesio Oseguera Cervantes during an attempt to capture him in Jalisco state was the highest-profile blow against cartels since the recapture of former Sinaloa cartel boss Joaquín “El Chapo” Guzmán a decade ago.