Costilla was often viewed as the "strongest leader" of the two, but collaborated with Antonio Cárdenas, who acted as representative of his jailed brother. However, Antonio died in an eight-hour shooting with the Mexican government forces on 5 November 2010, in the border city of Matamoros, Tamaulipas. Government sources claimed that this operation—where more than 660 marines, 17 vehicles, and 3 helicopters participated—left 8 dead: three marines, one soldier, and four gunmen, including Antonio Cárdenas. Other sources mention that one news reporter was also killed in the crossfire. This military-led operation was a result of more than six months of intelligence work. "Milenio Television" mentioned that the Mexican authorities had tried to apprehend Cárdenas Guillén twice before this incident, but that his personal gunmen had distracted the Mexican forces and allowed him to be escorted in his armored vehicle.