Forensic scientists in Austria say ‘excessive heat’ damaged DNA in teeth and bones of 17 sets of remains, Mexico attorney general’s office reports

This article is more than 5 years old

This article is more than 5 years old

Forensic scientists trying to identify remains believed to belong to some of 43 missing students missing in Mexico have failed to find sufficient usable DNA in them, officials said on Tuesday.

Austrian scientists are using mitochondrial DNA from the samples for genetic testing, in an effort to identify 17 sets of remains sent by the Mexican government.

But the Mexican attorney general’s office said the University of Innsbruck reported that “excessive heat” had damaged the mitochondrial DNA in fragments of teeth and bones, “at least to the point that normal methods cannot be used to successfully analyse them”.

The university has offered to use one last technique to identify the remains, but says there is a risk the testing may destroy the samples without obtaining any useful information.

The university said it expected the testing to take another three months, but could not give an exact date for results.

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The main risk is that the DNA extracted may be destroyed “without yielding any usable results”, prosecutors cited the university as saying.

Vidulfo Rosales, a lawyer representing families of the missing teachers college students, said prosecutors should have consulted the families of the missing students before making that decision.

“If these tests are done on the bone fragments, there could be practically nothing left,” Rosales told local media. “This is going to have an impact on the parents’ belief system … In rural tradition, mourning is highly symbolic, highly important.”

The university had previously found DNA in the remains that belonged to one of the 43 students who were detained and disappeared in the southern state of Guerrero in September. Prosecutors say the students were turned over to a drug gang that killed them and then incinerated their bodies on a fuel-fed pyre, before crushing the charred remains and dumping them in a river.

Authorities sent only 16 sets of remains to Austria, saying the rest were so badly deteriorated there was no chance of identifying them.

In all, 43 students are missing and are believed to have been murdered by drug gangs linked to local police.

The students, who were all enrolled in a rural teacher’s college known for its leftist politics, disappeared after they were reportedly attacked by municipal police and members of the Guerreros Unidos gang in the city of Iguala on 26 September.

There has been little definitive news about the students since then, but the investigation has indicated the students may have been killed, incinerated and then thrown in a river. Parents of the missing students are skeptical of this theory, insisting that the search continue.

Scientists from the National Autonomous University of Mexico have said that evidence from the supposed crime scene did not support the theory of a mass funeral pyre.

Authorities have arrested about 100 people since the disappearance, which has sparked an uproar in Mexico.

The arrests include local police, Iguala’s mayor and his wife, as well as the sister of a notorious drug trafficker and a suspected member of the Guerreros Unidos cartel.