Mexican authorities remain convinced that many of the 43 students who disappeared last year were killed and incinerated at a rubbish dump.
The Mexican attorney general’s office made the claim one day after an independent experts’ report said the incident did not happen.
Tomas Zeron, the director of Mexico’s criminal investigation agency, said that although there may have been errors in the initial investigation, they remain confident in the forensic science and the conclusion, adding that 100 investigators were involved.
Mr Zeron said: “We can’t be wrong.”
The students disappeared on September 26 2014, in the southern state of Guerrero.
Francisco Cox, one of the experts on the independent commission sent by the Inter-American Commission on Human Rights, told Milenio television that it is possible the students were burned elsewhere, but not at the dump.
In response to the report, attorney general Arely Gomez said she would order a new examination of what happened at the dump.
Eber Omar Betanzos Torres, deputy attorney general for human rights, said discussions were under way to select a group of pre-eminent investigators to make a third examination of the dump.
He said: “The attorney general’s office has always been interested in meeting the highest international standards, which implies carefully reviewing all of the profiles of those who make up the group ... with the best profile of neutrality, impartiality, transparency to offer total certainty.”
The independent experts’ report dismantled the government’s long-held official version and found numerous problems in the investigation.
Parents of the students have long refused to accept the government’s version.
Only one student was successfully identified from a bone fragment that the government said was thrown with other remains reduced to ash into a river.
The independent panel hired their own fire expert to study the scene.
He concluded that it was not possible that a fire of the magnitude necessary to reduce the bodies to ash had occurred at the dump.
Mexico government insists students were incinerated http://t.co/Q5koNbHmJA— AFP news agency (@AFP) September 7, 2015
The experts’ report put forward another possible motive for the attack, that one of the buses the students seized in Iguala was carrying a drugs load.
The city is a known hub for opium paste which is ferried out of surrounding mountains.
Mexican president Enrique Pena Nieto said he is willing to meet with the students’ parents and independent experts.
“I want to know the truth,” he said at an event in the central state of Puebla.
The Mexican government has agreed to extend the experts’ term so they can conclude their investigation.