The infighting in Los Zetas referred to confrontations between two factions in that criminal organization, Mexico's most violent, one led by Heriberto Lazcano Lazcano, alias El Lazca and the other led by Miguel Treviño Morales, alias Z-40. The rumors of the split appeared in mid-2012, when public banners and music videos on the web alleged betrayals between the two leaders. After the death of Lazcano it was confirmed that the leaders were not confronting each other, but rather that some men within Morales' faction did not want him as leader.
The split of Los Zetas began in 2010, when a regional leader of the organization disobeyed orders and killed 72 illegal immigrants and nearly 200 people in the northeastern Mexican city of San Fernando, Tamaulipas. In August 2011, several low-level Zeta members went into a casino in northern Mexico and set the place on fire. In the attack, which was a retaliation for the owner's failure to pay for "protection", 52 people were killed. The massacre was among the deadliest in Mexico's drug war and brought attention from the government. The mastermind of the attack turned out to be a mid-level leader who had carried out the attack without the approval of the top echelon. In mid-2012, a regional cell disobeyed Morales' commands and dumped 49 decapitated bodies on a roadside; Morales had ordered his henchmen to abandon the bodies in a city's main square and not outside the city limits.
Unlike other traditional criminal organizations in Mexico, a large portion of Los Zetas income comes from local operations. Drug trafficking makes up at least 50% of their revenue (other sources say less). The Zetas were more prone to activities such as kidnapping, extortion, theft and piracy. This decentralized structure opened the gang to internal splits, given the influence of low-level and regional leaders.
The violent and aggressive Morales had begun to take over Los Zetas' assets and depose Lazcano in early 2010. In the beginning, Lazcano was happy to have Morales in his ranks, but he underestimated him and gave him too much power. They rarely met, probably once a month. As tensions grew they spoke only via mobile phone. Morales' active role got him the loyalty and respect of many gang members and eventually many stopped payments to Lazcano. They lived in different parts of the country and aside from work, they had little in common. Morales preferred violence, while Lazcano was more business-like. Lazcano reportedly wanted Los Zetas to be less of a problem for the Peña Nieto government; in contrast, "[Treviño Morales] is someone who wants to fight the fight." This does not imply, however, that Lazcano "is a saint, but [Treviño Morales] seems to get his basic enjoyment by committing the most incredibly sadistic acts."