The Zetas now Mexico's largest drug gang. Who are they?

The Zetas are former elite military members who deserted the army and began serving as the armed wing of the Gulf Cartel in the 1990s. But when those two groups split in early 2010, the Zetas became their own organization, rising today to become one of two dominant players in the drug trade in Mexico. They control much of the east of the country, while their rivals, the Sinaloa Federation, control the west. The Zetas received international attention in Sept. 2011, after 35 corpses were left on a busy roadside during rush hour in the port of Veracruz.  The so-called "Zeta-killers," a group of hooded men who appeared on YouTube claiming that society was fed up with the brutal tactics of the Zetas, claimed responsibility.