Government officials knew that the now-famous group of Mexico's 43 students would be attacked by police in September but failed to stop it, according to a recently published investigation by Mexican magazine Proceso. The magazine's story, disputed by police and not yet verified by other news agencies, was based on leaked government documents that show federal law enforcement was tracking the students' movements before the alleged massacre earlier this year. The report contradicts Mexican President Enrique Peña Nieto's insistence that the federal government had nothing to do with the kidnapping, the Guardian reported.

“We have information that proves the federal government knew what was happening in the moment it was happening and participated in it,” reporter Anabel Hernández told the Huffington Post. “The government has tried to hide this information.”

Proceso's investigation, done in partnership with the University of California at Berkeley's investigative reporting program, is likely to further anger Mexican activists protesting what they see as a corrupt government incorrectly handling the case.

The 43 students have been missing since Sept. 26, when they left their teaching college in Iguala, Guerrero, to protest a speech by the mayor's wife and ended up in a confrontation with police. Officers allegedly turned the 43 students over to drug cartel Guerreros Unidos to be murdered and disposed of. The incident is still under investigation, but the remains of the first student was identified last week, the Huffington Post reported. Nearly 80 people have been arrested in connection with the students' kidnapping and probable death.

The federal government has previously said that Iguala Mayor José Luis Abarca ordered the initial police attack on the students, but the Proceso article tells a different story. It says federal and state officers knew the students' location and actually collaborated in their shooting.

"There is no way that the government of Peña Nieto can claim it did not know what was happening," read a loosely translated news article on Univision.

The magazine story also intimates that the government has tortured at least five witnesses in its investigation of the case. Some people were beaten, and one was electrocuted, Hernández told the Huffington Post.