The son of one of Sinaloa cartel kingpin Joaquin "El Chapo" Guzman's closest associates pleaded guilty to drug-trafficking charges in the US this week. 29-year-old Damaso Lopez Serrano pleaded guilty to drug-smuggling charges in a federal court in San Diego on January 10th, admitting he oversaw the shipment of thousands of pounds of meth, cocaine, and heroin to the United States. According to Business Insider, there are already signs the son is cooperating with US authorities.