The remains of another of 43 missing student teachers has been identified by forensic experts at the University of Innsbruck in Austria, Mexico's attorney general has said.
Arely Gomez said the student is Jhosivani Guerrero de la Cruz of the town of Omeapa, in the southern state of Guerrero, where the students disappeared nearly a year ago.
He is the second to be identified after Alexander Mora Venancio was identified last December.
The students disappeared on September 26, 2014, at the hands of local police while they were hijacking buses for transportation to a demonstration.
The government said they were detained by police in Iguala and Cocula and given to a drug gang and incinerated in a giant pyre at a rubbish dump.
The government says the ashes were then bagged and dumped into a nearby river. The attorney general's office said earlier this year that most of the remains were too charred to extract DNA material.
An independent panel of experts from the Inter-American Commission on Human Rights last week questioned key parts of the government's investigation, saying that a fire hot enough to incinerate 43 bodies did not occur in the dump.
Gomez said the remains of Guerrero de la Cruz were found in one of the bags in the river. She said there were 72-to-1 odds that the bone fragment belonged to someone related to Guerrero de la Cruz's mother.
Felipe de la Cruz, spokesman for the families, said they had just been told on Wednesday of the latest identification by a team of Argentine experts also working on the case at the request of the families.
Those experts received the information from the laboratory in Innsbruck and told the parents that it was not a certainty, he said.
The Argentine experts said they did not fully trust the result, de la Cruz said.
The Argentine experts maintain that they do not know where the bag came from and cannot confirm it came from the Cocula dump as the government says.
"It is not 100 percent certain," de la Cruz said. "So for us it is still not believable."
De la Cruz said news of the identification came as a shock to the families, including the parents of the boy. The families are currently in Mexico City.