Mexico's armed forces on Wednesday arrested a top boss of the Zetas drug cartel in charge of operations in three states along the US border, who was a right-hand man of the cartel chief. The military said the arrest of the unidentified suspect was made in Saltillo, Coahuila state. He is considered the Zetas' operational chief in Coahuila, Nuevo Leon and Tamaulipas states, and a right-hand man of cartel chief Heriberto Lazcano, the national defense office said.