2011–12 in the Mexican drug war

[3] Eye-for-an-eye fighting between Los Zetas and the Sinaloa Cartel began in the fall of 2011 in Veracruz, a strategic smuggling state with a large Gulf port.

[11] The Blog del Narco reported on September 21 that the message was signed by Gente Nueva, an enforcement group which worked for Sinaloa boss Joaquín Guzmán Loera.

[12] On 27 September the Jalisco New Generation Cartel released a video claiming that they had carried out the attacks on Los Zetas, however, and were planning to take over Veracruz.

[23] In response to the killings in Veracruz, Los Zetas left 26 bodies (16 burned to death) in abandoned vehicles in Sinaloa on 23 November.

[27] Authorities initially thought that the victims were police officers because their clothing resembled that of a special-operations unit,[27] but they concluded that the uniforms were not those of a police agency,[27] A message was left behind by the killers blaming authorities for cooperating with Sinaloa Cartel boss Joaquín Guzmán Loera, also known as "El Chapo".

[35][36] Los Zetas responded to the 2012 Nuevo Laredo massacres[37][38] by leaving the dismembered remains of 18 people in a Toyota Sienna and Ford EcoSport near U.S. retiree communities in Chapala, Jalisco, south of Guadalajara.

[39][40][41] Eighteen heads were found with the dismembered bodies; some had been frozen, others were covered with lime, and the rest were in an advanced state of decomposition.

[41] One hundred ninety-three people were killed by Los Zetas at the La Joya ranch in the municipality of San Fernando.

[45] Authorities investigating the massacre reported bus hijackings on Mexican Federal Highway 101 in San Fernando, and the kidnap victims were later killed and buried in 47 clandestine mass graves.

[48] The dismembered remains of 14 men were found on 17 April 2012 in plastic bags inside a Chrysler Voyager in the border city of Nuevo Laredo.

[50] Authorities said that they found a "message signed by a criminal group," but did not release its contents[51] or indicate if those killed were members of Los Zetas or the Gulf Cartel.

[52] According to CNN México, the message said that the group intended to "clean up Nuevo Laredo" by killing Zeta members.

[55] Twenty-three bodies (14 decapitated and nine hanged from a bridge) were discovered in Nuevo Laredo in an escalation of violence by rival drug gangs on the U.S.

[61][62] With the bodies was a message, reportedly signed by El Chapo, demanding that Nuevo Laredo mayor Benjamín Galván and other municipal and state leaders and public-safety officials recognize his and the Sinaloa Cartel's presence in the region.

[70] In response to the Gulf Cartel attacks, Los Zetas left 14 mutilated bodies in an abandoned bus in a Ciudad Mante shopping-center parking lot.

[71] The bodies of ten men and four women, reported at about 9 a.m. on 23 June 2012, were left with a message to the Gulf Cartel[71] which was not revealed by authorities.

[76] Nuevo León governor Rodrigo Medina said on 20 February 2012 that 30 prisoners escaped during the riot,[77] but the number was reduced to 29 four days later.

[79] One of the fugitives, Óscar Manuel Bernal (known as "La Araña", or the Spider), was considered by authorities to be "extremely dangerous" and was believed to be the leader of Los Zetas in Monterrey Municipality.