San Fernando police delivered detainees to the Zetas drug gang, according to a newly-declassified memo.

As demonstrators across Mexico take to the streets to protest the government’s involvement in the September 2014 disappearance of 43 students in Iguala, Guerrero, a case bearing many of the same grim hallmarks is getting renewed attention.

Today, in a new article for The Nation, I examine newly-declassified evidence of police involvement in the 2011 San Fernando massacre and what it all means for access to information on human rights cases in Mexico.

In August 2010, the Zetas criminal group abducted and killed 72 people pulled from buses traveling the highways near San Fernando, Tamaulipas, a town more than 1,000 kilometers northeast of Guerrero. The remains of 193 people were discovered buried in dozens of mass graves in the same part of the state the following April. Members of the Zetas and 17 San…