Mexican Cartel Strategic Note No. 33: Pueblos Unidos Launch Sophisticated Prison Break Allegedly Using Coches Bomba (Car Bombs) or IEDs
Daniel Weisz Argomedo, Nathan P. Jones, John P. Sullivan, and Robert J. Bunker
An armed cell composed of ten members using high caliber weapons and six vehicles, two of which were reported to have been set on fire as a distraction, broke into the jail (Centro de Readaptación Social de Tula – Tula Social Correctional Center or CERESO) in Tula, Hidalgo, on 1 December 2021. The cell helped nine inmates escape including the presumed leader of the Pueblos Unidos (United Towns or Villages), José Artemio Maldonado Mejía, Alias “El Michoacano,” “El R” or “El Rabias.” Maldonado Mejía is an alleged head of the huachicloero (petroleum theft) enterprise known as the Cártel Pueblos Unidos. Numerous media reports mention the use of car bombs or explosives during the operation.
“The criminals proceeded to release the inmates in the city of Tula.” Source: Twitter, 1 December 2021, https://twitter.com/El_Universal_Mx/status/1466151379228110848?s=2.
Key Information: “Participaron al menos 10 sujetos con armas exclusivas del Ejército en fuga de reos en Tula: Fiscalía Hidalgo.” El Universal. 1 December 2021, https://www.eluniversal.com.mx/estados/en-fuga-de-reos-en-tula-sujetos-usaron-armas-exclusivas-del-ejercito-fiscalia-hidalgo:
En el operativo que permitió la fuga de 9 reos del Centro de Readaptación de Tula, entre estos “El Michoacano”, presunto líder huachicolero, habrían participado al menos diez personas que usaron armas exclusivas del Ejército y seis vehículos, informó Alejandro Habib Nicolás, procurador de Justicia de Hidalgo.
En entrevista con Carmen Aristegui, el procurador mencionó que en Hidalgo no se había tenido registro de “una operación de un comando de esta naturaleza con ese poder de fuego que mostraron con armas exclusivas del ejército, ya estamos hablando inclusive de que se pudiera tratar de grupos de la delincuencia organizada”…
…José Artemio Maldonado Mejía, alias “El Michoacano”, “El R” o “El Rabias”, es presuntamente líder del Cártel Pueblos Unidos, que estaría dedicado principalmente al robo de combustible en la región de Hidalgo.
Key Information: Key Information: “Commando uses a dynamite-loaded vehicle for Hidalgo jailbreak; 9 inmates freed.” Mexico News Daily. 1 December 2021, https://mexiconewsdaily.com/news/hidalgo-jailbreak-car-bombs/:
Hidalgo state authorities said armed men rammed vehicles into a Hidalgo prison and freed nine inmates early Wednesday. Aided by the detonation of two apparent car bombs in nearby streets, the audacious jailbreak occurred at approximately 4:00 am at a prison in Tula, located about 100 kilometers north of Mexico City. Local media reports said the vehicle used to ram down the prison door was loaded with dynamite.
One of the freed inmates was the alleged head of a fuel theft gang called Pueblos Unidos. José Artemio Maldonado Mejía, known as “El Michoacano,” was arrested in México state last week on fuel theft, kidnapping, homicide, and drug trafficking charges. The Hidalgo Security Ministry said that there were clashes between the armed men and prison personnel, adding that two police officers were injured and were receiving medical care.
Hidalgo Interior Minister Simón Vargas said, “an armed group burst into the prison aboard several vehicles,” adding that “it’s worth noting that near the prison, two vehicles were burned as part of the criminal group’s operation, as a distraction.” The use of car bombs by Mexican criminal organizations is rare, but one such attack in Ciudad Juárez, Chihuahua, in 2010, killed three people. In 2019, outside the Pemex refinery in Salamanca, Guanajuato.
Key Information: David Agren, "Gangsters use vehicles to ram into Mexico prison and free nine inmates." The Guardian. 1 December 2021, https://www.theguardian.com/world/2021/dec/01/mexico-prison-break-car-bombs
Mexican gangsters used a convoy of vehicles (including a truck with homemade armor-plating) to ram their way into prison before opening fire at guards and rescuing nine inmates. Several other vehicles were also set on fire in the spectacular plot targeting the jail in the central city of Tula. The escapees include José Artemio Maldonado Mejía, alias “El Michoacano”, the leader of a local crime organization known as Pueblos Unidos.
Tula is the site of a massive Pemex refinery. Criminal groups have increasingly tapped petroleum pipelines to siphon off gasoline – which is later fenced to motorists or sold to petrol stations – often with threats for failure to purchase. Pueblos Unidos, led by El Michoacano, is thought to be one of the leading groups behind petrol theft in Hidalgo state.
Mexican criminal groups have often raided prisons over the past 15 years, bursting into the facilities or impersonating security forces to free inmates. The cartels are increasingly deploying weapons such as explosives dropped from drones and launching brazen mobilizations to rescue captured colleagues.
Key Information: “Esta es la «tanqueta» que se utilizó para liberar reos del penal de Tula.” 24 Horas. 1 December 2021, https://www.msn.com/es-mx/noticias/mexico/esta-es-la-«tanqueta»-que-se-utilizó-para-liberar-reos-del-penal-de-tula/ar-AARlR1p:
En la fuga de al menos 9 reos del penal de Tula, Hidalgo, se usó una tanqueta hechiza. Aquí te contamos con qué la armaron.
El comando ocupó un camión de gas, al que soldaron una placa de metal en la parte posterior para tumbar las bardas del penal.
En las imágenes que se han difundido en redes sociales, se puede observar la camioneta roja con el logo “Reyes Gas”.
Además de la tanqueta, se utilizó una camioneta tipo Jeep Cherokee donde se trasladaban los reos, y al menos dos coches bomba que se usaron como distracción (uno fue detonado cerca del hospital regional Tula-Tepeji y el otro en la colonia El Llano).
Key Information: “Paso a paso, la insólita fuga de nueve reos del penal de Tula, Hidalgo: utilizaron coches bomba.” Infobae. 1 December 2021, https://www.infobae.com/america/mexico/2021/12/01/paso-a-paso-la-insolita-fuga-de-nueve-reos-del-penal-de-tula-hidalgo-utilizaron-coches-bomba/:
Eran las 04:00 horas de la madrugada del miércoles en el Centro de Readaptación Social de Tula, Hidalgo. Un comando armado—abordo de una tanqueta—burló las medidas de seguridad del penal, desató un tiroteo y amagó a los custodios para liberar al reo José Artemio Maldonado Mejía, alias el Michoacano, el R y/o Rabias, identificado como líder del grupo armado Pueblos Unidos.
El primer obstáculo antes de conseguir la libertad del capo eran las bardas del penal, las cuales derribaron con una camioneta utilizada para distribuir gas, y la cual fue modificada. En el trayecto habían varios barrotes rotos y candados abiertos. Algunas de las imágenes reveladas este miércoles, muestran tres vehículos en llamas—dos de ellos coches bomba—.
Key Information: Nathaniel Janowitz, “Wild Video Shows Brazen Prison Break-In Mexico.” Vice. 3 December 2021, https://www.vice.com/en/article/dyppba/hidalgo-mexico-gang-boss-prison-break:
A gang sprung nine prisoners during a daring escape using a jerry-rigged truck as a battering ramand car bombs in the central Mexican state of Hidalgo on Wednesday. The highly coordinated prison break allegedly focused on freeing José Artemio Maldonado, the violent kidnapping and fuel theft ring leader…
…Security footage quickly spread on social media of the truck, fitted with a makeshift metal plow of some sort, crashing through a garage door into a prison in the city of Tula around 4 am. Wednesday. Once inside, several armed individuals threatened the guards, who released the inmates. Nine prisoners then fled, reportedly all members of the Pueblos Unidos gang, in six separate waiting vehicles. As they sped off, two car bombs went off in different parts of the city—apparently to function as a distraction while the escapees and their accomplices engaged in firefights with the cops.
Authorities later discovered a third car with explosives that possibly malfunctioned in another part of the city, and tire spikes were found on roads leading to the prison aimed at impeding police from arriving at the scene of escape. Two agents were injured in the ensuing chaos, according to authorities.
An armed cell composed of ten members using high caliber weapons and six vehicles, of which two were set on fire as a form of distraction, broke into the CERESO (jail) in Tula, Hidalgo, on 1 December 2021, at ~0400 hrs. (4:00 am). The group helped nine inmates escape including José Artemio Maldonado Mejía, Alias “El Michoacano” the presumed leader of the Cártel Pueblos Unidos, a group active in huachicolero (fuel theft). The Cártel Pueblos Unidos started as autodefensas (a self defense group) in opposition to the Cártel de Jalisco Nueva Generación (CJNG).
The commandos used a modified LPG (Liquidfied Petroleum Gas) transport truck fitted with a makeshift metal plow to break through the main garage door into the prison. Once inside, ten armed individuals threatened the guards, who released the inmates. Reportedly all of the inmates that escaped were members of the Pueblos Unidos group, that were able to flee in six separate waiting vehicles. As they exited, two car bombs went off simultaneously in different parts of the city to serve as a distraction while the escapees and their accomplices engaged in firefights with police. Authorities later discovered a third car with explosives that possibly malfunctioned in another part of the city, and tire spikes (caltrops) were found on roads leading to the prison aimed at impeding security forces from arriving at the scene of the escape. Two agents were injured in the ensuing chaos, according to authorities.
So far, this incident represents the most organized and well-equipped prison break conducted in the state of Hidalgo and the increasing use of high-caliber weapons, caltrops, and car bombs by organized crime in Mexico. The attack also follows a long history of prison breaks in Mexico that continue to showcase the weaknesses of the Mexican penal system. Many questions remain in terms of who organized the jailbreak? Why was José Artemio Maldonado Mejía, Alias “El Michoacano” the apparent target of the jail break? State authorities are still investigating the attack, but this event seems to fall into the rising pattern of highly organized and coordinated attacks conducted by organized crime in Mexico.
Breakouts and Weaknesses of the Penal System
The weakness of the Mexican penal system has regularly been exposed by organized crime. Prison escapes in Mexico began to escalate in frequency as the war on drugs intensified. Between 2009 and 2012, eight massive prison breaks occurred in Mexico in Nuevo Leon, Veracruz, Zacatecas, and mainly Tamaulipas. Of these eight prison breaks, the number of escaped prisoners went as low as 32 and as high as 450. In many of the cases, well-armed commandos broke into the jail themselves, and in several cases, they found prison personnel had assisted with the escapes. Prison breaks in Mexico have served several strategic purposes for organized crime. Massive breakouts allow cartels to recover fellow members from incarceration. There have also been prison breaks that only target a cartel leader.
The most infamous case of a cartel leader escaping prison in Mexico is that of El “Chapo” Joaquín Guzmán, who escaped from jail on two separate occasions. The first time he escaped was 19 January 2001, from the high-security prison of Puente Grande in Jalisco. He was able to escape with the help of a prison employee that hid him in a laundry cart and helped him escape. After 13 years on the run, Guzmán would be captured on 22 February 2014, at a hotel in Mazatlán, Sinaloa, and was placed in the most secure prison in Mexico known as el Altiplano. Guzmán would then orchestrate one of the most complex prison breaks in the history of Mexico. On 11 July 2015, he escaped from his prison cell through the bathroom floor where a 1,500-meter tunnel had been built with a motorbike on tracks that allowed him to escape once again. The investigation into the breakout found that Guzmán had help from both the outside and some of the prison personnel.
The Sinaloa Cartel illustrated a new strategic purpose for prison breaks on 17 October 2019, when an operation to capture Ovidio Guzmán López (one of Joaquín Guzmán's sons) turned Culiacán, Sinaloa into a battleground. As the Sinaloa Cartel took over the city, they began to cause commotion and distractions across the city to liberate Ovidio Guzmán. One of these distractions was the escape of 51 convicts from the Aguaruto prison in Culiacán. Throughout the past decade, prison breaks in Mexico have exposed the weaknesses of the Mexican penal code and have also shown a variety of strategic purposes behind them including freeing leaders, causing distractions/ and operational chaos, etc. With an already overburdened judicial system that can only send 7 percent of those detained for organized crime to stand trial, a prison system that is understaffed and underfunded only serves to increase impunity and degrade the judicial system in Mexico.
Mexican prisons have critical deficiencies such as understaffing of security personnel, no preventative measures for looting, injuries, escapes, or homicides. A report by the National Commission for Human Rights (Comisión Nacional de los Derechos Humanos – CNDH) found that in 54% of Mexican jails, the prisoners control the prison through violence towards the rest of the population in prison. The report also found that more than half of the prisons in Mexico are severely overpopulated and understaffed. There are no actions to prevent or attend to violence in prisons where drug traffickers impose their laws and get special privileges. As Mexican correctional facilities continue to be understaffed, underfunded, and in most cases controlled by criminals, we can expect the Mexican judicial system to continue to be undermined and a rise in prison breaks in Mexico.
The History of Car Bombings in Mexico
Another concerning trend from the prison break in Hidalgo was using car bombs in the breakout. Contemporary Mexican cartel use of car bombs began in mid-July 2010 and has since escalated significantly in tactics, techniques, and procedures (TTPs). Mexican drug traffickers have recently used car bombs to attack police, troops, and rival gangs as the drug war increases in violence. An example of this is the 15 July 2010 attack on Federal police in Ciudad Juárez that ambushed police using a primitive IED and killed four people. Between 2008 and 2012, 18 car bomb incidents were registered in Mexico, signaling an escalation in car bombs used by organized crime.
Robert J. Bunker and John P. Sullivan note some lessons learned from Colombian cartel car bombs. “First, car bombs were not only used in Colombia as a warning to others but also in an anti-personnel role to kill government agents, rival traffickers, and civilians; and in an anti-infrastructure role to damage and destroy public, commercial, and private facilities and buildings.” The other lesson learned was that although violence spread to some key distribution cities in the United States, the level of violence remained restrained, and no record of any cartel car bombings took place in the United States. Colombia is a crucial case study to understand how the increase in TTPs in Mexico can escalate and evolve if they are not successfully addressed. As the drug war continues to rage violently in Mexico, we can expect an increase in violent TTPs and a continual evolution of strategies to employ these car bombs, as is the case with the Hidalgo prison break.
The recent prison break operation for the criminal El Michoacano in the state of Hidalgo is representative of numerous trends in Mexican organized crime. First, it is part of the increased use of IEDs by Mexican cartels in vehicles and other delivery mechanisms such as drones. Second, it is part of the tactical trend of impeding responding law enforcement through the use of narco blockades or caltrops. Third, El Michoacano is representative of the tendency of organized crime figures to hold multiple criminal positions across groups and move between groups and Mexico’s complex criminal landscape. El Michoacano was also reportedly a leader of Los Emes a group known for human smuggling and kidnapping in Northwest Mexico.
Fourth, the criminals hired for the operation were also paid surprisingly little for such a complex and risky operation. One of the men paid to assist in the operation was later captured by authorities and offered a bribe of 9,000 pesos or about 450 US dollars that we would have been paid for the operation. This is consistent with previous indications that the price to have someone killed in Mexico is consistently low. This is a worrying trend given that this was a sophisticated prison escape involving timed detonations of car bombs and a tactically successful operation.
This operation by the Pueblos Unidos demonstrates the weakness of the Mexican penal system, the cheap availability of sophisticated criminal actors, and the tactical diffusion that occurs as a second order effect of high value targeting and the fragmentation of Mexican organized crime into sophisticated networked operators. These operations may become more common and more sophisticated, e.g. involving aerial drone strikes in addition to vehicle borne IEDs. This incident is also representative of the broader conflict between the Cártel de Jalisco Nueva Generación (CJNG) and the Sinaloa cartel and their affiliates. The Cártel Pueblos Unidos allies with the Sinaloa cartel against the CJNG as they battle for domination in Michoacán.
David Agren, “Gangsters use vehicles to ram into Mexico prison and free nine inmates.” The Guardian. 1 December 2021, https://www.theguardian.com/world/2021/dec/01/mexico-prison-break-car-bombs.
“Commando uses dynamite-loaded vehicle for Hidalgo jailbreak; 9 inmates freed.” Mexico News Daily. 1 December 2021, https://mexiconewsdaily.com/news/hidalgo-jailbreak-car-bombs/.
“Esta es la «tanqueta» que se utilizó para liberar reos del penal de Tula.” 24 Horas. 1 December 2021, https://www.msn.com/es-mx/noticias/mexico/esta-es-la-«tanqueta»-que-se-utilizó-para-liberar-reos-del-penal-de-tula/ar-AARlR1p.
“Gang rams vehicles into prison, springs 9 inmates.” Washington Post. 1 December 2021, https://www.washingtonpost.com/world/gang-rams-vehicles-into-prison-springs-9-inmates/2021/12/01/7fc8c226-52bb-11ec-83d2-d9dab0e23b7e_story.html.
Nathaniel Janowitz, “Wild Video Shows Brazen Prison Break In Mexico.” Vice. 3 December 2021, https://www.vice.com/en/article/dyppba/hidalgo-mexico-gang-boss-prison-break.
“Participaron al menos 10 sujetos con armas exclusivas del Ejército en fuga de reos en Tula: Fiscalía Hidalgo.” El Universal. 1 December 2021, https://www.eluniversal.com.mx/estados/en-fuga-de-reos-en-tula-sujetos-usaron-armas-exclusivas-del-ejercito-fiscalia-hidalgo
“Paso a paso, la insólita fuga de nueve reos del penal de Tula, Hidalgo: utilizaron coches bomba.” Infobae. 1 December 2021, https://www.infobae.com/america/mexico/2021/12/01/paso-a-paso-la-insolita-fuga-de-nueve-reos-del-penal-de-tula-hidalgo-utilizaron-coches-bomba/.
 In English, the title reads: “At least 10 individuals with exclusive Army weapons participated in the escape of inmates in Tula: Hidalgo Prosecutor's Office.” The text reads: “In the operation that led to the escape of nine inmates from the Tula Readaptation Center, among them ‘El Michoacano,’ the alleged leader of the drug cartel, at least ten people used exclusive army weapons and six vehicles, informed Alejandro Habib Nicolás, Hidalgo's Attorney General, in an interview with Carmen Aristegui. […] In an interview with Carmen Aristegui, the prosecutor mentioned that in Hidalgo there had never been a record of ‘a commando operation of this nature with the firepower they showed with exclusive army weapons, we are even talking about organized crime groups’... […] ...José Artemio Maldonado Mejía, alias ‘El Michoacano,’ ‘El R’ or ‘El Rabias,’ is allegedly the leader of the Cártel Pueblos Unidos, which is mainly dedicated to fuel theft in the Hidalgo region.”
 in English, the title reads: “This is the ‘tanqueta’ [improvised armored vehicle] used to free inmates from Tula prison.” The text reads: “In the escape of at least 9 inmates from the prison in Tula, Hidalgo, a fake tank was used. Here we tell you what they used to build it. […] The commandos used a gas truck, to which they welded a metal plate on the back to knock down the prison walls. […] In the images that have been disseminated on social networks, you can see the red truck with the ‘Reyes Gas’ logo. […] In addition to the tankette, a Jeep Cherokee van was used to transport the prisoners, and at least two car bombs were used as a diversion (one was detonated near the Tula-Tepeji regional hospital and the other in the El Llano neighborhood).”
 In English, the title reads: “Step by step, the unusual escape of nine inmates from Tula prison, Hidalgo: they used car bombs.” The text reads: “It was 4:00 a.m. Wednesday morning at the Social Rehabilitation Center in Tula, Hidalgo. An armed commando—on board a tankette [improvised armored vehicle]—circumvented the prison’s security measures, unleashed a shootout and threatened the guards in order to free the inmate José Artemio Maldonado Mejía, alias el Michoacano, el R and/or Rabias, identified as the leader of the armed group Pueblos Unidos (United Peoples). […] The first obstacle before the capo’s release was the prison walls, which they broke down with a truck used to distribute gas, and which had been modified. Along the way there were several broken bars and open padlocks. Some of the images revealed on Wednesday show three vehicles in flames—two of them car bombs—.”
 For an early report, see “Grupo armado explota tres coches bomba en el Cereso de Tula [Armed group explodes three car bombs in Tula Cereso (jail)].” Infobae. 1 December 2021, https://www.infobae.com/america/mexico/2021/12/01/tres-coches-bomba-explotaron-esta-madrugada-en-el-cereso-de-tula-presuntamente-fue-para-liberar-a-capo-de-pueblos-unidos/. According to that report, “La Secretaría de Seguridad Pública de Hidalgo confirmó que un grupo de personas armadas irrumpió en el penal a bordo de vehículos con artefactos explosivos. Presuntamente fue para liberar a una capo de ‘Pueblos Unidos’ [The Hidalgo Public Security Secretariat confirmed that a group of armed individuals broke into the prison aboard vehicles with explosive devices. Allegedly it was to free a ‘Pueblos Unidos’ drug lord].”
 “Participaron al menos 10 sujetos con armas exclusivas del Ejército en fuga de reos en Tula: Fiscalía Hidalgo [At least 10 individuals with exclusive Army weapons participated in the escape of inmates in Tula: Hidalgo Prosecutor's Office].” El Universal. 1 December 2021, https://www.eluniversal.com.mx/estados/en-fuga-de-reos-en-tula-sujetos-usaron-armas-exclusivas-del-ejercito-fiscalia-hidalgo
 “José Artemio Maldonado, ‘el ‘Michoacano’: quién es el supuesto líder de Pueblos Unidos que se fugó del penal de Tula [José Artemio Maldonado, 'el 'Michoacano': who is the alleged leader of Pueblos Unidos who escaped from Tula prison.” Infobae. 1 December 2021, https://www.infobae.com/america/mexico/2021/12/01/jose-artemio-maldonado-el-michoacano-quien-es-el-supuesto-lider-de-pueblos-unidos-que-se-fugo-del-penal-de-tula/.
 “Pueblos Unidos: el grupo de autodefensas que le hace frente al CJNG será desarmado por las autoridades [Pueblos Unidos: self defense group facing CJNG to be disarmed by authorities].” Infobae. 29 June 2021, https://www.infobae.com/america/mexico/2021/06/29/pueblos-unidos-el-grupo-de-autodefensas-que-le-hace-frente-al-cjng-sera-desarmado-por-las-autoridades/.
 Nathaniel Janowitz, “Wild Video Shows Brazen Prison Break-In Mexico.” Vice. 3 December 2021, https://www.vice.com/en/article/dyppba/hidalgo-mexico-gang-boss-prison-break.
 “Cronología: Las fugas masivas en cárceles de México [Chronology: Massive jailbreaks in Mexico's prisons].” Aristegui Noticias. 17 September 2012, https://aristeguinoticias.com/1709/mexico/cronologia-las-fugas-masivas-en-mexico/.
 “Las veces que se escapó el Chapo Guzmán de prisión [The times Chapo Guzman escaped from prison].” El Universo. 24 April 2021, https://www.eluniverso.com/larevista/salud/las-veces-que-se-escapo-el-chapo-guzman-de-prision-nota/.
 Alexis Ortiz, “Narcos y plagiarios, entre los fugados en Culiacán [Drug traffickers and kidnappers among those on the run in Culiacán].” El Universal. 20 October 2019, https://www.eluniversal.com.mx/nacion/asesinos-y-secuestradores-los-fugados-en-culiacan.
 Arturo Angel, “Más de mil 300 detenidos por crimen organizado, pero solo 7% va a juicio por ese delito [More than 1,300 arrested for organized crime, but only 7% go to trial for that crime].” Animal Politico. 9 December 2019, https://www.animalpolitico.com/2019/12/detenidos-crimen-organizado-juicio-vinculados/.
 Rubén Aguilar, “Cárceles en México [Jails/Prisons in Mexico].” Animal Politico. 11 May 2016, https://www.animalpolitico.com/lo-que-quiso-decir/carceles-en-mexico/.
 Robert J. Bunker and John P. Sullivan, “Cartel Car Bombings in Mexico.” Letort Paper. Carlisle Barracks. US Army War College, Strategic Studies Institute. 2013: pp. 1-53, https://publications.armywarcollege.edu/pubs/2238.pdf.
 Ibid. and Robert J. Bunker and John P. Sullivan, Eds. Criminal Drone Evolution: Cartel Weaponization of Aerial IEDs. Bloomington: Xlibris, 2021.
 Nathan P. Jones, “Bacterial Conjugation as a Framework for the Homogenization of Tactics in Mexican Organized Crime.” Studies in Conflict & Terrorism. Vol. 44, no. 10. 3 October 2021: pp. 855–884, https://doi.org/10.1080/1057610X.2019.1586356.
 Op. cit. Janowitz at Note 8.
 Veneranda Mendoza, “Cae presunto implicado en fuga de ‘El Michoacano’; le habrían pagado 9 mil pesos. [Alleged suspect involved in the escape of ‘El Michoacano’ is captured; he was allegedly paid 9,000 pesos].” Proceso. 2 December 2021. https://www.proceso.com.mx/nacional/estados/2021/12/2/cae-presunto-implicado-en-fuga-de-el-michoacano-le-habrian-pagado-mil-pesos-276845.html.
 See Minute 1:36:00 in National Law Enforcement Officers Museum. “Witness to History: Operation Shadow Game.” YouTube. 27 April 2016, https://www.youtube.com/watch?time_continue=7&v=gwH6eeOwC4k.
 Guadalupe Fuentes López. “El CJNG y el de Sinaloa se pelean el control de 9 de los 10 municipios más violentos [CJNG and Sinaloa fight for control of 9 out of 10 most violent municipalities].” Sin Embargo. 6 December 2021, https://www.sinembargo.mx/16-12-2021/4079839.
 “Pueblos Unidos: el grupo de autodefensas que le hace frente al CJNG será desarmado por las autoridades [Pueblos Unidos: self-defense group facing CJNG to be disarmed by authorities].” Infobae. 29 June 2021, https://www.infobae.com/america/mexico/2021/06/29/pueblos-unidos-el-grupo-de-autodefensas-que-le-hace-frente-al-cjng-sera-desarmado-por-las-autoridades/.
Robert J. Bunker and John P.Sullivan, Eds. Illicit Tactical Progress: Mexican Cartel Tactical Notes 2013–2020, Bloomington: Xlibris, 2021
John P. Sullivan and Robert Bunker, “Cartel Car Bombings in Mexico.” Letort Paper. Carlisle Barracks. US Army War College, Strategic Studies Institute. 2013: pp. 1-53.
Nathan P. Jones, “Bacterial Conjugation as a Framework for the Homogenization of Tactics in Mexican Organized Crime.” Studies in Conflict & Terrorism. Vol. 44, no. 10. 3 October 2021: pp. 855–884.