Miguel "Z-40" Trevino Morales has taken over as the top leader of Los Zetas, replacing Heriberto "El Lazca" Lazcano Lazcano, according to several media reports. Stratfor sources have said the leadership transition was due to Lazcano's failing health.
Lazcano is reportedly suffering from a terminal illness and has gradually reduced his operational role in the criminal group over the past several months, allowing Trevino to step into the top position. This purported transition may explain why recent anti-Los Zetas operations by rival cartels and law enforcement have focused on Trevino. Given Lazcano's alleged health condition, a leadership transition likely would have been inevitable at some point in the near future, and Trevino has demonstrated an ability to handle the challenges facing Los Zetas, namely internal schisms, offensives by other cartels and pressure from the Mexican military.
While Lazcano was the undisputed leader of the cartel, Trevino maintained a significant role as a presumed second in command, overseeing operations in critical locations such as Nuevo Laredo. Trevino has likely been running the majority of Los Zetas' operations for months prior to the reported transition.
Although it does not appear Lazcano and Trevino have become rivals as reports suggested in July, Trevino still could face internal conflicts in the future, which could trigger increased violence in regions where Los Zetas operate. Given his near-decade long leadership of Los Zetas, Lazcano likely retains a certain amount of control over the group, not to mention possessing extensive information on Trevino and his activities. This would make Lazcano a valuable asset for any of Trevino's rivals, inside or outside Los Zetas, should Lazcano split from Trevino's organization in the future.
Additionally, Trevino is already dealing with an internal schism in Zacatecas, San Luis Potosi, Coahuila, and Nuevo Leon led by Ivan "El Taliban" Velazquez Caballero, a regional Los Zetas boss who is challenging Trevino's authority in those territories. Should Velazquez garner additional support from other Los Zetas leaders, this regional intra-cartel turf war could expand.
Since Trevino has likely overseen the group's activities for some time, few operational changes should be expected. Besides Los Zetas' rivals focusing their information operations on Trevino, there have been few overt signs of any transition, suggesting Lazcano may have handed operations over without significant resistance. If the leadership transition has taken place as reported, Trevino seems fully capable of handling the group's operations as competently as his predecessor did.