Gulf Cartel
Osiel Cárdenas, leader of the Gulf Cartel at the time was captured by the Mexican Army in a battle between Gulf Cartel gunmen and the Army on March 14, 2003, in Matamoros. Though subsequently incarcerated at Penal del Altiplano (La Palma), México's top security prison, it was widely believed that he continued to have control over Gulf Cartel business from within prison walls.