Los Zetas (pronounced [los ˈsetas], Spanish for "The Zs") is a fractured Mexican criminal syndicate and designated terrorist organization, known as one of the most dangerous of Mexico's drug cartels. They are known for engaging in brutally violent "shock and awe" tactics such as beheadings, torture, and indiscriminate murder. While primarily concerned with drug trafficking, the organization also ran profitable sex and gun rackets. Los Zetas also operated through protection rackets, assassinations, extortion, kidnappings and other illegal activities. Although the organization was founded in Matamoros, Tamaulipas, they eventually established themselves in Nuevo Laredo, directly across the border from Laredo in Texas during the mid-2000s. The origins of Los Zetas date back to the late 1990s, when commandos of the Mexican Army deserted their ranks and began working as the enforcement arm of the Gulf Cartel. In February 2010, Los Zetas broke away and formed their own criminal organization, rivalling the Gulf Cartel.
They were at one point Mexico's largest and most expansionist drug cartel in terms of geographical presence, overtaking their rivals, the Sinaloa Cartel, in physical territory. However, since the mid/late 2010s Los Zetas have become fragmented and seen its influence diminish, with most factions absorbed by their regional opposition or eliminated. As of March 2016, Grupo Bravo (Bravo Group), Los Talibanes (The Talibans), and Zetas Vieja Escuela (Old School Zetas) had formed an alliance with the Gulf Cartel against Cártel del Noreste (Cartel of the Northeast).
Although fragmented, the Zetas' and Gulf Cartel's smaller offshoots, with their power struggles, continue to create a situation of extreme violence in their home state of Tamaulipas. As of 2025, The U.S. Department of State lists Tamaulipas alongside five other states in Mexico with a Level 4: Do Not Travel advisory.
Los Zetas was named after its first commander, Arturo Guzmán Decena, whose Federal Judicial Police radio code was "Z1", a code given to high-ranking officers.
After Osiel Cárdenas Guillén took control of the Gulf Cartel in 1997, he found himself in a violent turf war. Decena deserted in 1997 and began working for Cárdenas in 1999 to protect from rival drug cartels and the Mexican Army. Decena lured more than thirty deserters from the elite Grupo Aeromóvil de Fuerzas Especiales (GAFE) to become his personal bodyguards, and later, as his mercenary wing. Some of these former GAFE members reportedly received training in commando and urban warfare from the Israeli and U.S. Special Forces.
Once Guillén consolidated his power, he expanded the responsibilities of Los Zetas, which began to organize kidnappings, protection rackets, extortion, securing cocaine supply and trafficking routes known as plazas (zones) and executing its foes, often with extreme violence. However, in November 2002, Decena was killed in a military action at a restaurant in Matamoros, Tamaulipas, allowing Heriberto Lazcano ("Z3") to take control of the group. In response to the rising power of the Gulf Cartel, the rival Sinaloa Cartel established Los Negros, an enforcer group similar to Los Zetas but not as complex or successful. Upon the arrest of Guillén in March 2003 and his extradition in 2007, the Zetas took a more active leadership role within the Gulf Cartel and their influence grew within the organization.
The Zetas' membership ranged from corrupt federal, state, and local police officers, and former U.S. Army personnel, to ex-Kaibiles, the special forces of the Guatemalan military. Over time, many of the Zetas' original thirty-one members were killed or arrested; a number of younger men filled the vacuum, but that left the group far from the efficiency of their paramilitary origins.
Los Zetas was partially responsible for a qualitative increase in the brutality of the violence seen during the modern Mexican drug wars. Unlike other cartels, the Zetas did not buy alliances so much as terrorize their enemies. Because the cartel was quite new at the time, it competed with more established cartels by using extreme violence and cruelty as a form of psychological warfare. They tortured victims, strung up bodies, and slaughtered indiscriminately. They preferred to take military-style control of territory, holding it through sheer force and exploiting its criminal opportunities. Although their military training was diluted over time, their brutality was not. Rival cartels struggling against the Zetas began to adopt some of their tactics, further ramping up violence in the country. As other organized crime groups subsequently copied the Zetas' brutal and extreme methods to ensure their survival, this escalated the violence in Mexico to new heights. Some of these new torture methods and hyper-violent executions included practices such as flaying and castration.
Following the capture and extradition of Cárdenas, Los Zetas became so powerful that they outnumbered and outclassed the Gulf Cartel in revenue, membership, and influence by 2010. As a result of this imbalance, the Cartel tried to curtail their own enforcers' influence and ended up instigating a civil war. In addition, the Gulf Cartel, through its narco-banners in Matamoros and Reynosa, accused Los Zetas of expanding their operations to murder, theft, extortion, kidnapping – actions that the Gulf Cartel allegedly disagreed with. Los Zetas countered by posting their own banners throughout Tamaulipas, noting that they had carried out executions and kidnappings under orders of the Gulf Cartel and they were originally created for that sole purpose. In addition, Los Zetas charged that the Gulf Cartel was scapegoating them for the murders of innocent civilians.
Reports vary as to who triggered the formal split and why. Some sources claim that Guillén, brother of Cárdenas and one of the successors of the Gulf Cartel, was addicted to gambling, sex, and drugs, leading Los Zetas to perceive his leadership as a threat to the organization. Other reports mention, however, that the divide occurred due to a disagreement on who would take on the leadership of the cartel after the extradition of Cárdenas. The candidates from the Cartel were Guillén and Jorge Eduardo Costilla Sánchez, while Los Zetas wanted to hand the leadership to their own head, Lazcano. The Cartel also reportedly began looking to form a truce with the rival Sinaloa Cartel, which Los Zetas did not want to recognize, allegedly preferring an alliance with the Beltrán-Leyva Cartel.
Samuel Flores Borrego, a lieutenant of the Cartel, killed Zetas lieutenant Sergio Peña Mendoza alias "Comandante Concord", due to a disagreement over the drug corridor of Reynosa, whom both protected. Los Zetas demanded that the Cartel hand over the killer, but they refused.This refusal marked the beginning of the split between the two organizations: within months, Los Zetas moved to seize territory and drug routes previously controlled by their former Gulf Cartel allies, igniting the broader Los Zetas–Gulf Cartel conflict that dominated organized crime in northeastern Mexico through 2010 and beyond.
When the hostilities began, the Cartel joined forces with its former rivals, the Sinaloa Cartel and La Familia Michoacana, aiming to take out Los Zetas. Consequently, Los Zetas allied with the Beltrán-Leyva Cartel, the Juárez Cartel, and the Tijuana Cartel.
In early 2010, Miguel Treviño Morales, the former second-in-command of Los Zetas, had reportedly taken the leadership of the Zetas and displaced Lazcano. Lazcano was initially content to have Morales in his ranks, but reportedly gave Morales too much power and underestimated his violent nature. Morales' active leadership gained him the loyalty and respect of many in Los Zetas, leading many to eventually stop paying their tributes to Lazcano. Los Zetas were inherently an unstable organized crime group with a long history of brutal violence. Another splinter group was formed also named Sangre Nueva Zeta (New Blood Zeta), allying themselves with the Jalisco Cartel as an armed wing. In March 2019, Texas Republican congressman Chip Roy introduced a bill that would list the Cartel Del Noreste faction of Los Zetas, Jalisco New Generation Cartel and Gulf Cartel as foreign terrorist organizations. Those plans were halted at the request of Mexican president Andrés Manuel López Obrador, but in February 2025, State Department designated the Cártel del Noreste, one of the main splinter groups remaining from the Zetas, as a foreign terrorist organization.