Mexican Army soldiers escort Luis Jesus Sarabia Ramon (C), aka 'El Pepito' or 'Z-44', an alleged leader of Los Zetas drug cartel, during his presentation to the press on January 13, 2012 in Mexico City.

"Los Zetas" are the most technologically advanced, sophisticated, and dangerous Mexican gang, according to the U.S. government, and those qualities have made the group the most feared drug cartel in Mexico. Now, they may be that country's most feared energy producer, too.

In the past three years, Los Zetas have taken effective control of Mexico's Coahuila region in the north, along the border of Texas. The gang covertly entered the region, and under the threat of extreme violence against those who don't cooperate with them, have brought almost every aspect of commerce, politics, and business under their direct influence.