[3] By forming alliances with Colombian drug traffickers, García Ábrego coordinated marijuana and cocaine shipments into the U.S. and helped consolidate the Gulf Cartel as a multibillion-dollar criminal enterprise.

[7][8] In mid-1999,[9] Cárdenas Guillén ordered the murder of his friend Salvador Gómez Herrera (alias "El Chava"),[10] the last man in line in the Gulf Cartel's leadership structure.

[11] To protect himself from rival gangsters and security forces,[12] Cárdenas Guillén formed a private army known as Los Zetas, which consisted of former military officials.

[14] In August 1996, the Drug Enforcement Administration (DEA) launched an anti-drug investigation known as Operation Limelight that initially targeted Mexico's Juárez Cartel and Amado Carrillo Fuentes.

[17] On 9 June 1999,[a][16] Cárdenas Guillén threatened to kill Abraham Rodríguez,[19] an undercover Cameron County Sheriff's Office investigator working with the U.S. Customs Service in Brownsville.

[24] According to Bermúdez Núñez, the head representative of the newspaper, Mario Díaz, met with Cárdenas Guillén, his lawyer Galo Gaspar Pérez Canales, and Gulf Cartel member Víctor Manuel Vázquez Mireles to discuss bribery payments.

[15] At around 2:30 p.m. on 9 November 1999,[21] DEA and FBI agents Joe DuBois and Daniel Fuentes traveled to Matamoros to gather intelligence on the operations of the Gulf Cartel.

[29] The agents called the DEA offices in Houston using their mobile telephone and asked them to investigate the Texan license plates of a cherry-red Explorer, one of the vehicles that was following them.

[48] Mexico's attorney general Jorge Madrazo Cuéllar and PGR anti-drug chief Mariano Herrán Salvatti met with the U.S. presidential cabinet hours later and discussed the incident.

They concluded in these conversations that Cárdenas Guillén was hiding in Monterrey with his wife and two children: Celia Marlén and Osiel Jr. As the investigation tightened, they discovered his family travelled in a Jetta, BMW, and an X Terra, and identified the schools their kids attended.

Cárdenas Guillén stayed at multiple hotels throughout the year but eventually grew tired and bought a home in Bosques de las Lomas, Mexico City.

[49] On 18 November 1999, DuBois and Fuentes met with a PGR head Héctor Daniel Dávalos Martínez in San Antonio, Texas, and told him what had occurred in the standoff.

[53] DuBois also recounted the incident to Kevin C. Whaley, former head of the DEA offices in Houston, telling him the reason they did not leave their vehicle when Cárdenas Guillén ordered them to do so.

[19] On 28 July 2000, during the 48th Annual Awards Ceremony of the U.S. Department of Justice, DuBois and Fuentes were recognized by the U.S. Attorney General Janet Reno for their "exceptional heroism".

She stated that the agents reminded Cárdenas Guillén of the consequences of his actions and showed "professionalism and courage" despite being outnumbered and facing life-threatening circumstances.

[15] On 14 December 2000, U.S. Department of State assistant deputy Wendy Chamberlin announced a US$2 million bounty for Cárdenas Guillén, Garza Rendón, and Medrano Rodríguez.

This announcement was made alongside an indictment issued in Brownsville charging Cárdenas Guillén and seven of his associates of drug trafficking and assault against federal agents.

[15] "We are sending a clear and strong message that no one can threaten or harm a federal agent with impunity," DEA chief Donnie R. Marshall said in the press release.

[62] The sanction was also extended to 11 other suspected drug traffickers across the world, including Álvarez Tostado, Sher Afghan, Miguel Caro Quintero, Chang Ping Yun, Joseph Gilboa, Joaquín Guzmán Loera, Jamiel Hamieh, Ismael Higuera Guerrero, Nasir Ali Khan, Óscar Malherbe de León, and Alcides Ramón Magaña.

The third shootout broke out near Matamoros International Airport when a group of gunmen tried to rescue Cárdenas Guillén and prevent the military from transporting him to Mexico City.

[71] After the third shootout, the military erected checkpoints and carried out vehicle inspections on the highways connecting Matamoros with Reynosa, Ciudad Victoria, and Playa Bagdad.

It also marked a radical shift in modus operandi of organized crime groups in Mexico; a shootout of this scale had not been seen in previous arrests of high-profile drug lords.

[76] The arrest was planned in nearly absolute secrecy; the only Mexican officials aware of Cárdenas Guillén's capture were Fox, the Secretary of Defense Ricardo Clemente Vega García, and Attorney General Rafael Macedo de la Concha.

[71] The Mexican government stated that tracing his whereabouts was a difficult task;[f] during the investigation, they discovered he had at least 300 individuals working under him and protecting him from law enforcement in various parts of Mexico.

[90][91] De la Cruz Reyna was arrested in Polanco, Mexico City, on 30 August 2007;[92] he was extradited to the U.S. on 31 December 2008,[93][94] and sentenced to 11 years in prison on 10 October 2012.

[98] Cárdenas Guillén and Arellano Félix orchestrated plans to destabilize La Palma, and were placed under 24-hour surveillance with limited visits from family members.

[99] In October 2003 Cárdenas Guillén planned a hunger strike with other inmates after complaining that prison authorities were limiting the availability of water for their daily showers.

[105] The same month, he ordered the execution of six prison guards in Matamoros; according to investigators, the attack was intended to show the government he was still capable of instigating violent acts.

[106] On 31 December 2005, high-ranking Sinaloa Cartel leader Arturo Guzmán Loera was killed in La Palma; investigators suspected Cárdenas Guillén may have planned the attack.

[113] According to the U.S. Department of Justice, Cárdenas Guillén led a vast criminal empire that supplied multi-ton shipments of cocaine and marijuana from Mexico to the U.S., resulting in millions of dollars in drug proceeds.