Originally published on December 25, 2014, at NationofChange.org

After years of silence, the office of Mexico’s Attorney General declassified a document admitting police officers had participated in the kidnapping and massacre of hundreds of migrants throughout northern Mexico. While working for Los Zetas drug cartel, police provided illicit protection, assisted in kidnappings, and turned a blind eye to the investigation of numerous mass graves. Caught in a turf war between the Gulf Cartel and the Zetas, at least 314 migrants have died at the hands of the police and cartels.

According to a recently declassified memo sent from the office of Mexico’s Attorney General to The National Security Archive, local police in the city of San Fernando in northern Mexico have been working for the Zetas for years. A DEA cable from 2009 noted many Zetas had been recruited from an elite Mexican Army unit known as the Grupo Aeromóvil de Fuerzas Especiales (GAFE). No longer operating as the enforcement arm of the Gulf Cartel, the Zetas expanded into new territory and asserted control through murder, intimidation, and corruption.

In August 2010, San Fernando police officers set up roadblocks and pulled at least 72 mainly Central American migrants off intercity buses. Instead of detaining the migrants, police officials handed them over to the Zetas who extorted fees for safe passage across the border and forced them work as drug mules. The Zetas executed everyone who could not afford to pay or refused to smuggle drugs across the border. The bodies of 58 men and 14 women from Central and South America were later discovered at a remote ranch in San Fernando.

In a cable from the U.S. Consulate in Monterrey on March 23, 2010, the consulate reported that the governor of Nuevo Leon suspended 81 police officials working for the Zetas and setting up roadblocks around the city. On May 21, 2010, the consulate reported that 165 out of approximately 1,000 state police had been dismissed in recent months due to their ties to drug cartels. In April 2011, the U.S. Consulate in Matamoros noted that 17 Zetas and 16 members of the San Fernando police were arrested in connection with the murders of the bus passengers and hundreds of bodies found in dozens of mass graves.

One of the officers arrested, Álvaro Alba Terrazas, told investigators, “I know that police and transit officials in San Fernando help the Zetas organization, because rather than take detainees to the Pentágano, which is to say the municipal jail, they would deliver them to the Zetas. The truest one [“mero bueno”] is an elderly police officer and another named Óscar Jaramillo, who receive money from the organization to collaborate.”

Between April and May of 2011, at least 193 bodies were discovered in 47 mass graves across San Fernando. The victims had mostly been Central American migrants attempting to cross the border into Texas to the north. A year later, 49 human torsos were found in the neighboring state of Nuevo Leon.

According to the U.S. Consulate in Monterrey, intense fighting between the Zetas and the Gulf Cartel made travel extremely dangerous along the highly contested narcotrafficking roads north from Monterrey to the U.S. border. With the assistance and participation of local police, the Zetas have been responsible for committing multiple acts of extortion, hijacking, kidnapping, robbery, carjacking, drug trafficking, and murder.

Although the Mexican government has been suppressing any information regarding the massacres for several years, the National Security Archive and two transparency advocacy groups in Mexico have succeeded in the declassification of one document. The memo names 17 San Fernando police officers and a dozen suspected members of the Zetas involved in the massacres. Citing a Mexican law permitting agencies to withhold information pertaining to an ongoing investigation, the government prosecutor was overridden by another provision in the law requiring the release of information on grave violations of human rights.

In response to the abduction of 43 students last seen in police custody on September 26, protests and riots have ignited across Mexico demanding the resignation of government officials and the safe return of the students. At least 80 people have been arrested including 44 police officers from Cocula and Iguala suspected of working for a local drug gang called Guerreros Unidos. According to the Mexican government, Guerreros Unidos killed the students, burned their bodies, and dumped the remains into a river.