A scathing report issued Sunday accuses the Mexican government of stonewalling an international probe into the disappearance of 43 students in September 2014, and Mexican police of torturing suspects in the case. 

The 608-page report from the Inter-American Commission on Human Rights—the fruit of an oft-obstructed, year-long investigation—was unveiled “at an emotional press conference on Sunday attended by some of the relatives of the missing students,” according to VICE.

No high-ranking government officials showed up.

“There seems to be no limit to the Mexican government’s utter determination to sweep the Ayotzinapa tragedy under the carpet,” said Erika Guevara-Rosas, Americas director at Amnesty International, in response to the report.

Forty-three student-teachers, studying at a college in rural Ayotzinapa, went missing on Setember 26, 2014. The official government narrative is that that the students were abducted by a drug cartel and incinerated at a nearby trash dump under orders from the local mayor.

But the outside experts’ report is skeptical of that storyline:

The report criticized the forensic investigations of human remains and evidence of fire at the garbage dump in the town of Cocula, Guerrero, saying that prosecutors had provided little evidence there ever could have been a fire a big enough at the site. It said the government had stuck by its version the students were killed and incinerated at the dump, despite evidence to the contrary, like 17 tree trunks found at the scene that showed little or no evidence of fire.

The report also found that the cell phone of one student had been used to send a message to his parents hours after he had supposedly been killed and his phone destroyed.