The Argentine Forensic Anthropology Team found no evidence of the kind of fire required to support the government's earlier conclusion that the students were incinerated at a garbage dump. This is the second external study to demolish that version.
Scenes from the huge demonstration in central Mexico City on the one-year anniversary of the mass disappearance of 43 young men from the Ayotzinapa Normal School.
Tens of thousands of protesters march in Mexico City on rainy day to show indignation over the missing students remains strong
The parents met with President Enrique Peña Nieto with emotions running high, two days ahead of the first anniversary of the disappearance of their children.
With the case of the 43 missing students still looming over the state, Guerrero officials now say another probably mass disappearance took place after unknown men entered a town to 'free' it from a drug gang.
Journalist Sevgul Uludag has spent years searching for answers about thousands of people who disappeared during conflict between Greece and Turkey for control of Cyprus in the 1960s and 70s.
The case of the 43 missing students in Mexico has galvanized discussion and efforts to locate thousands of others who remain missing. Many of them are not included in official figures.
Dentures were found at the dump where the students were supposedly incinerated, among other anomalies detailed by the Argentine Forensic Anthropology Team. The attorney general struck back at the group, calling its assertions "speculation."
Mexican officials delivered a report to the UN committee on forced disappearances in Geneva this week, acknowledging the Ayotzinapa case as a sign that much more must still be done to prevent similar tragedies.