They're known as "Los Zetas (tags)
The men are known as the Zetas, former members of the Mexican army who defected to Mexico's so-called Gulf drug cartel in the late 1990s
FBI Intelligence Bulletin no. 89: Spying On Protestors (tags)
The FBI intelligence bulletin, disseminated on a weekly basis, provides law enforcement with current, relevant terrorism information developed from counterterrorism investigations and analysis. The intelligence bulletin does not contain threat warning information.