The trouble started January 18 when a Gulf cartel member killed top Zeta lieutenant Victor Mendoza. The Zetas demanded that the Gulf cartel turn over the killer, but the narco group refused. The Zetas, composed mostly of former elite military troops, had been the armed enforcers for the Gulf cartel since 2001. The Zetas have become more independent in recent years, and the all-out war between the two cartels indicates the split is apparently permanent.
Mexican marines stand during the presentation of Alberto Mendoza Contreras alias "The bad kid", a suspected leader of the Beltran Leyva cartel, in Monterrey March 19, 2010. Drug violence has exploded across Mexico since President Felipe Calderon came to power in late 2006 and set the army on smuggling gangs. Turf wars between rival cartels and security forces have killed nearly 19,000 people in three years, with the worst of the bloodshed seen in northern border cities. (Reuters/Daylife)
Students smile as they pose for pictures in front of a pile incinerated drugs at the 20th Cavalry Regiment military base in Ciudad Juarez March 18, 2010. More than two ton of narcotics, including marijuana, heroine and cocaine, were incinerated as part of the Chihuahua joint operation, in which the federal government sent thousands of soldiers to curb drug violence in Mexico's bloodiest city on the U.S. border. (Reuters/Daylife)
Soldiers escort Jose Alfredo Soto, a.k.a. "El 7," as he is presented to the press in Ciudad Juarez, Mexico, Wednesday, March 17, 2010. According to the army, Soto is an alleged member of the drug gang "La Linea" and is a suspect in the January massacre of 16 people in Ciudad Juarez, many of them teenagers. (AP/Daylife)