The Mexican army says it has dealt a significant blow to a powerful drug cartel, with the arrest of one of the cartel leader's security chiefs, as the latest outbreak of violence between warring groups has left at least 13 people dead.<br /><br />The army said on Monday that special military forces seized computer files and other data when they detained Felipe Cabrera Sarabia, a security chief of Joaquin "El Chapo" Guzman, head of the Sinaloa drug cartel.<br /><br />Al Jazeera's Franc Contreras reports from Mexico City.
