A new report by a human rights activist from Mexico tries to shed light light on how Los Zetas carried out two high-profile massacres in Mexico with almost complete impunity. The activist’s work confirms a three-month investigation by Breitbart Texas into the extermination and incineration of 300 victims in northern Mexico.

Over the weekend, Mexican activist Sergio Aguayo presented his report on the massacres by Los Zetas in the Mexican towns of Allende, Coahuila, and in San Fernando, Tamaulipas. The investigation provides harsh criticism of Mexico’s government for being complicit in the cover-up of the crimes.

Earlier this year, Breitbart Texas revealed the results of a three month investigation into the Massacre of Allende, where gunmen with the Los Zetas cartel kidnapped, tortured and used ovens, or 55-gallon drums to incinerate their victims. Mainstream media in the U.S. has ignored the Massacre of Allende.

The investigation by Breitbart Texas was based on personal interviews as well as U.S. and Mexican court documents that revealed that the leadership of Los Zetas sought to enact revenge on two high ranking associates who had turned themselves over to U.S. authorities in exchange for protection to become informants.

The perceived betrayal of the two associates was met with a swift response by the former leader of Los Zetas Miguel Angel “El 40” Trevino Morales and his brother Omar “El 42” Treviño Morales. The two men ordered the kidnapping murder of every person who was related to, knew or may have been an acquaintance of the turncoats.

After Breitbart Texas’ report, the Coahuila government was shamed into admitting publicly that between 100 and 150 of the murder victims had been incinerated inside the Piedras Negras prison in 55-gallon drums.

In his new report, Mexican activist Sergio Aguayo criticizes the apparent cover-up of the massacre by the Coahuila Government, since the case was largely ignored for more than three years. In contrast, Aguayo presents the swift response of the Mexican government of the Los Zetas execution of 72 illegal immigrants in San Fernando, Tamaulipas in 2010. In that case, in a matter of weeks, the Mexican military managed to arrest dozens of Zetas and corrupt cops tied to the case.

Due to his ongoing work in uncovering corruption, Aguayo has been sued by Coahuila’s former governor Humberto Moreira who claims that the activist has slandered him.

Ildefonso Ortiz is an award winning journalist with Breitbart Texas. He co-founded the Cartel Chronicles project and you can follow him on Twitter and on Facebook.