Miguel Ángel Treviño Morales (born 18 November 1970), commonly referred to by his alias Z-40, is a Mexican former drug lord and leader of the criminal organization known as Los Zetas.

Born into a family with six brothers and six sisters, Treviño Morales began his criminal career as a teenager, working for Los Tejas—a local gang from his hometown of Nuevo Laredo, Tamaulipas.

His fluent English and experience of moving contraband along the U.S.–Mexico border enabled him to be recruited in the late 1990s by the drug lord Osiel Cárdenas Guillén, who headed the Gulf Cartel and Los Zetas.

Around 2005, he was appointed as the regional boss of Los Zetas in Nuevo Laredo and was given the task to fight off the forces of the Sinaloa Cartel, which was attempting to take over the lucrative drug trafficking routes to the United States.

After successfully securing these routes in Nuevo Laredo in 2006, Treviño Morales was moved to Veracruz and appointed as the Zetas leader in the state after the death of the drug lord Efraín Teodoro Torres.

He also did chores for the local drug lord Héctor Manuel Sauceda Gamboa (alias El Karis), who later became his mentor; Treviño Morales eventually replaced him as Gulf Cartel leader in Nuevo Laredo.

Few details are known of Treviño Morales's life in Dallas;[10] the U.S. authorities believe he learned about "power, money, weapons and the vast consumer market for illegal drugs" while living in Texas.

Around 2005, Treviño Morales became the regional boss of Nuevo Laredo; he was in charge of fighting off the incursions of the Sinaloa Cartel, which was attempting to take control of the smuggling routes in the area.

The Laredo–Nuevo Laredo area is a lucrative smuggling route for narcotics because of the Interstate 35 highway, which serves as a strategic pathway to San Antonio, Austin, and Dallas for future drug distribution.

Under Treviño Morales, the organization smuggled immigrants to the United States, carried out extortions and kidnappings, sold bootlegged CDs and DVDs, and intimidated and/or killed residents who failed to cooperate with them.

[18][19] He was reassigned to the coastal state of Veracruz, shortly after high-ranking Zetas leader Efraín Teodoro Torres (alias Z-14) was killed in a gun battle at a local horse race.

[29] He was alleged to have favored a torture method known as el guiso (stew), in which people are stuffed into an oil barrel, doused with gasoline or diesel fuel, and set on fire to burn alive.

[33] Journalist Alfredo Corchado, head of The Dallas Morning News in Mexico, wrote in one of his books that Treviño Morales enjoyed eating out the hearts of his victims—even when they were still alive—because he believed that doing that would make him invincible among his enemies and authorities.

[36][37] Under Treviño Morales' leadership, Los Zetas were considered by the Drug Enforcement Administration (DEA) to be highly sophisticated, advanced, and one of the most dangerous criminal organizations operating in Mexico and the hemisphere.

La Compañía (The Company), a name used to describe the Gulf Cartel and Los Zetas as a conglomerate, remained in a loose cooperation until early 2010, when violence erupted between both groups.

[43][44] On 18 January 2010, several members of the Gulf Cartel kidnapped Víctor Peña Mendoza (alias Concord 3), a leader of Los Zetas and close associate and friend of Treviño Morales.

When he was held captive, Peña Mendoza was asked to switch alliances and join the Gulf Cartel, but he refused, earning a beating followed by execution, presumably carried out by Samuel Flores Borrego.

[45] Treviño Morales heard about the incident and issued an ultimatum to Flores Borrego and Gulf Cartel leader Jorge Eduardo Costilla Sánchez: Hand over the assassin of my friend, you son of a bitch ... You have until the 25th, if you don't comply, there will be war.

[48] With Treviño Morales as the second-in-command of the criminal organization, Los Zetas began killing Gulf Cartel members and other rival drug traffickers en masse and winning their territories.

[49][50] In 2011, however, Treviño Morales's criminal organization entered a new internal strife after Jesús Enrique Rejón Aguilar (alias El Mamito), one of their highest-ranking leaders, was arrested in July.

High-ranking Zetas leader Iván Velázquez Caballero (alias El Talibán) was arrested in September 2012, presumably set up either by rival gang members or gangsters aligned with a group related to Treviño Morales.

[49][56] After Velázquez's fall, a split off group known as Los Legionarios (The Legionaries) was born in Nuevo Laredo and vowed to bring down Treviño Morales for allegedly betraying him.

2 "Occidente," in Puente Grande, Jalisco, it was concluded that the characteristics mentioned by several witnesses, such as tattoos, body build, and scars, did not match those of the detainee, leading to the conclusion that they were two different individuals.

Regarding this issue, on September 17, 2024, during a press conference, Miguel Ángel Treviño Morales's lawyers argued that the detainee of the same name is not the leader of Los Zetas[74] but rather a namesake accused by the then Attorney General's Office of Mexico.

These rulings were confirmed in a new decision dated November 30, 2023, in case 295/2023 issued by the Collegiate Appeals Court of the Nineteenth Circuit, which again established that the detainee, named Miguel Treviño Morales, was not the one nicknamed "Z40."

To date, the United States Embassy has not responded to these disputes and has instead reinforced its extradition request to President Claudia Sheinbaum Pardo, alleging that Treviño Morales continues to control the Northeast Cartel.

[75] The act prohibited U.S. citizens and companies from doing any kind of business activity with him, and virtually froze all his assets in the U.S.[76] A month before his capture, U.S. authorities had been passing down information to their counterparts in Mexico that Treviño Morales was making frequent visits to the Nuevo Laredo border area to see his newborn baby.

[89] He was then imprisoned in Puente Grande, Jalisco, outside of the city of Guadalajara, until 30 June 2020, whereupon he was transferred to the Federal Center for Social Readaptation (Cefereso) 17, located in Buenavista Tomatlán, in Tierra Caliente, Michoacán.

At around 4:00 a.m. on 4 March 2015, Treviño Morales was captured inside a residence in Fuentes del Valle, an upper-class neighborhood in San Pedro Garza García, Nuevo León, by the Federal Police and the Mexican Army.

[102] Miguel's wife Juanita del Carmen Ríos Hernández was included in the Foreign Narcotics Kingpin Designation Act in February 2014, banning U.S. citizens from doing any kind of business activities with companies under her name.