The complexity of the attack showed that the CJNG had expertise in military tactics, guerrilla warfare, ambush and counter-ambush training, and in use of explosives.

[b][10] As the police units got to a curve, the CJNG gunmen opened fire at them with machine guns and grenade launchers from the side of the mountains.

[33] The report stated that the attack against the police was a retaliation for the 23 March death of Heriberto Acevedo Cárdenas (alias "El Gringo"),[h] a suspected regional leader of the CJNG.

[30][35] In addition, the report stated that the attack was provoked by the arrest of 15 suspected CJNG members following an assassination attempt against Francisco Alejandro Solorio Aréchiga, Jalisco's security commissioner, on 30 March.

[30] A day after the attack, Jorge Aristóteles Sandoval Díaz, the Governor of Jalisco, called for a meeting with several high-ranking government officials at the Municipal Palace of Guadalajara (es).

[39] He went into detail about the ambush, and gave the press more background on the possible motives behind the attack, including the death of El Gringo and previous arrests of suspected CJNG members as part of the murder attempt against him.

[i][37] This attack was unusual in the ongoing Mexican Drug War (2006–present) because large scale single-attacks against Mexico's security forces were uncommon.

[46] Jalisco was one of the four states in Mexico that President Enrique Peña Nieto (2012–2018) considered a priority for his national security initiative.

[49] The month before the ambush, on 19 March 2015, the CJNG attacked a convoy of the National Gendarmerie (es), a branch of the PF, in Ocotlán, Jalisco.

Investigators believe that the attacks were masterminded by Nemesio Oseguera Cervantes (alias "El Mencho"), the top leader of the CJNG and one of Mexico's most-wanted drug lords.

[63] Over 100 shots were fired from both sides,[64] but Solorio Aréchiga's bodyguards were able to repel the CJNG's armed aggression and help him come out of the shooting unharmed.

[63] Investigators confirmed that this was a direct assassination attempt against Solorio Aréchiga, and that it stemmed from the government crackdowns on the CJNG's leadership structure.

According to Luis Carlos Nájera Gutiérrez de Velasco, the Attorney General of Jalisco, the CJNG had at least 80 gunmen on their side.

[69][70] Nájera Gutiérrez de Velasco explained that the turning point of the attack occurred when the CJNG threw explosives attached to 20 liters of gasoline from the top of the mountains.

Nájera Gutiérrez de Velasco admitted that one of the biggest obstacles of the investigation was understanding how the CJNG found out the exact day, time, and place the police convoy was going to pass through the area where they were ambushed.

[69] Jalisco authorities believe that the attack was planned by members of the CJNG who were experts in military tactics, ambush and counter-ambush training, and guerrilla warfare.

[43] In addition, they stated that those who planned the attack were experts in explosives, which made them think that the CJNG had members with former military or police training with experience in such combat.

[71] Nájera Gutiérrez de Velasco told the press that investigators had evidence that the CJNG was recruiting foreign paramilitary gunmen as foot soldiers in Jalisco.

[75][77] Several hours after the ambush,[78] suspected CJNG gunmen based in Zacoalco de Torres killed Miguel Ángel Caicedo Vargas, the police chief of that municipality.

[80] The assassins stabbed cardboard onto the corpse with a written message warning law enforcement that he was killed for the death of El Gringo.

[83] Municipal authorities from Zacoalco de Torres refused to provide details on the murder, and did not say if they were planning to host a memorial ceremony for Caicedo Vargas.

The police department where Caicedo Vargas worked, which sat across the street from the convention center, placed a black ribbon in front of their main entrance.

[94] A larger ceremony was held again on 8 April in Tlaquepaque, Jalisco, this time with Governor Sandoval Díaz and the victims' families.

[106] On 11 April, Jalisco authorities told the press that investigators concluded that the prime suspect in the ambush was one of El Gringo's family members, who ordered the attack as a retaliation for his death.

According to government reports, this suspect was arrested on 19 June 2012 by the Mexican Army for allegedly being involved in organized crime and drug trafficking in Michoacán.

[108] On 21 June, an armed commando stormed the installations, subdued an officer from the Federal Investigation Agency (AFI), ordered him to open the prison cells, and rescued El Gringo's relative and another man.

When the PGR found out about the incident, they issued a national alert at the country's border exit stations to prevent them from leaving Mexico.

[111] According to government sources, El Duende was acting as El Gringo's successor in the CJNG's leadership structure,[112] and was suspected of being involved in multiple attacks against security forces, including the incident in San Sebastián del Oeste, Guachinango, and one in San Martín de Hidalgo, Jalisco in 2014, where the CJNG carried out an attack against the PF and the Army.

[113] On 12 March 2016, state authorities in Lagos de Moreno, Jalisco arrested Miguel Pérez Contreras,[p] a suspected CJNG member who was reportedly involved in the Guachinango and San Sebastián del Oeste attacks.

In addition, they discovered that he was in contact with a female based in the United States who helped recruit people from American private security companies to work for the CJNG.