Mario Cárdenas Guillén is the brother of the Mexican drug lord who was the former leader of what group?
Osiel Cárdenas Guillén Osiel Cárdenas Guillén (born May 18, 1967) is a former Mexican drug lord and the former leader of the Gulf Cartel (Spanish: "Cártel del Golfo" ) and Los Zetas. Originally a mechanic in Matamoros, Tamaulipas, where he was born, he entered the Gulf Cartel by helping Juan García Abrego, the capo at the time; when García Ábrego was arrested in 1996, some infighting erupted within the cartel. Osiel Cárdenas eventually took control by killing his friend and contender Salvador Gómez, earning Cárdenas the nickname ""El Mata Amigos"" (The Friend-Killer).
Joint Operation Nuevo León-Tamaulipas Joint Operation Nuevo León-Tamaulipas is an anti-drug joint operation in two Mexican states of Tamaulipas and Nuevo León by Federal Police and the Mexican Armed Forces. The objective of the joint operation is to eliminate Los Zetas and Gulf Cartel operations in the area. So far a large number of cartel members have been either killed or arrested. Recently Los Zetas and the Gulf Cartel have broken relations and started fighting each other.