An independent report has dismantled the Mexican government's investigation into last year's disappearance of 43 teachers' college students, saying the prosecutor's contention that they were incinerated in a giant pyre never happened.
The report has fuelled the anger of parents who have gone nearly a year not knowing what happened to their sons.
Attorney General Arely Gomez, who was not in office during the initial investigation, says that in light of the report she will call for a new forensic investigation of the municipal garbage dump where the initial probe concluded the 43 were burned to ash beyond identification.
Parents of the students are demanding a meeting with President Enrique Pena Nieto, whose reputation and popularity has been undermined by the case.
"We will not accept another lie from the government," said Blanca Nava Velez, mother of Jorge Alvarez Nava.
While the government said the September 26 attack was a case of mistaken identity, the report said it was a violent and coordinated reaction to the students, who were hijacking buses for transportation to a demonstration and may have unknowingly interfered with a drug shipment on one of the buses.
Iguala, the city in southern Guerrero state where the attacks took place, is known as a transport hub for heroin going to the United States, particularly Chicago, some of it by bus, the report said.
"The business that moves the city of Iguala could explain such an extreme and violent reaction and the character of the massive attack," the experts said in the report delivered to the government and the students' families during a public presentation, where some chanted "It was the state!".
The report means that nearly a year after the disappearance, the fate of 42 of the students remains a mystery, given the errors, omissions and false conclusions outlined in more than 400 pages by the experts assembled by the Inter-American Commission on Human Rights.
Only a charred bone fragment of one of the 43 has been identified and it wasn't burned at the high temperature of an incineration, contrary to Mexican investigators' claims.
"We have no evidence to support where the disappeared are," said Carlos Beristain, a Spanish medical doctor on the team.
The report recommends that authorities rethink their assumptions and lines of investigation, as well as continue the search for the students and investigate the possible use of public or private ovens to cremate the bodies.
It also recommends investigating the possible drug angle and who coordinated and gave the orders for the attacks - all unknowns nearly a year later.
Pena Nieto said via his Twitter that he has given instructions for investigators to take into account the findings of the report, which dealt another blow to the Mexican government in a case that has already brought international outrage and protests.
The attack and disappearance of the 43 at the hands of officials became a pivotal moment in Pena Nieto's administration, which started fast out of the blocks three years ago with a series of key political and economic reforms.
But the slow response to the case of the 43 and the implausibility of the government's version of the events has eroded the credibility of his government.
To date, authorities have detained more than 100 people, the majority of them local police. The former Iguala mayor, Jose Luis Abarca, is also in custody and has been identified with his wife as having ordered the attack.
The experts say that may be true, but it's still not clear.