The Gulf Cartel, which has controlled the area since the 1930s, is suspected of being involved in the deadly incident. Alex Cruz/EPA/ShutterstockHeading up the current iteration of the Gulf Cartel is Jose Alfredo Cárdenas-Martinez, nicknamed El Contador. “They deserted the military, were named the Zetas, and the Gulf Cartel became militarized.”As the new enforcement arm of the Gulf Cartel, the Zetas helped the group to beef up its extortion and protection footprint. Despite the fact the Gulf Cartel ranks as the oldest in Mexico, running such an enterprise is complicated. Getty ImagesSmith agreed, and has a deeper theory as well: “Gulf Cartel has some police officers on their payroll.