Investigators are now certain that 43 college students missing since September were killed and incinerated after they were seized by police in southern Guerrero state, the Mexican attorney general said Tuesday.
It was the first time Jesus Murillo Karam said definitely that all were dead, even though Mexican authorities have DNA identification for only one student and a declaration from a laboratory in Innsbruck, Austria, that it appears impossible to identify the others.
The attorney general cited confessions and forensic evidence from an area near a garbage dump where the Sept. 26 crime occurred that showed the fuel and temperature of the fire were sufficient to turn 43 bodies into ashes.
"The evidence allows us to determine that the students were kidnapped, killed, burned and thrown into the river," Murillo Karam said in a press conference that included a video reconstruction of the mass slaying and of the investigation into the case.
He added that "there is not a single shred of evidence that the army intervened ... not a single shred of evidence of the participation of the army," as relatives of the victims have claimed.
Murillo Karam's explanation seemed unlikely to quell the controversy and doubts about the case, in which the federal government has been criticized for acting slowly and callously. Thousands of people demonstrated in Mexico City Monday night, demanding the students be returned alive.
"They pretty much gave the same story as they had given two months ago. There are not many additional details," said analyst Alejandro Hope. "They are searching for closure but I'm not sure they're going to get it."
The attorney general has come under attack from many quarters, including the students' relatives and fire experts, who say the government's version of what happened is implausible. Family members are still searching in hopes of finding the students alive.
The Argentine Forensic Anthropologists, an independent team hired by parents to work with federal investigators, told The Associated Press on Sunday that there is still not "sufficient evidence" to link the charred remains found by authorities in a river in the town of Cocula to what happened at the garbage dump.
Valentin Cornelio Gonzalez, 30, brother-in-law of missing student Abel Garcia Hernandez, said the shifting theories of what happened to the students have left him and other family members not believing anything that officials say.
"On a personal level, it makes me mad because this is what they've always done," he said of Tuesday's announcement. "There's no chance that the parents are going to believe the PGR (saying) that they're dead. ... They are going to look for them alive."
Murillo Karam said the conclusion was made based on the testimony of a key suspect arrested two weeks ago, Felipe Rodriguez Salgado, who said he was called to get rid of the students. There are also 39 confessions. Based on samples of gasoline, diesel and steel from burned tires, he said, they concluded that the amount of heat from the fire and the location could have kept the blaze going for hours, and that the remains were crushed afterward.
Authorities say they were burned the night of Sept. 26 and over the next day, and their incinerated remains were bagged up and thrown into a nearby river. The remains in the bags found in the river had traces of the garbage dump where the fire occurred, Murillo Karam added.
The scene of the crime was an 800-meter (yard) ravine that resembled a furnace, said criminal investigations chief Tomas Zeron.
Murillo Karam said the information was based as well on 386 declarations, 487 forensic tests, 16 raids and two reconstructions.
So far 99 people have been detained in connection with the crime, including the former mayor of Iguala, Jose Luis Abarca.
Murillo Karam said the motive was that the members of a local gang, the Guerreros Unidos, believed the young men were rival gang members when they hijacked some public transit buses in Iguala. But many of the suspects testified that they knew the men were students. The students, known for commandeering buses and taking over toll booths to support their leftist causes, said they were taking the buses for transport to an upcoming demonstration in Mexico City.
"They thought they were infiltrated," Murillo Karam said at the press conference, adding that there is no indication that the students were part of any criminal group.
The case has sparked protests inside and outside Mexico over the four months since the students disappeared, and has forced the Mexican government to turn its attention from touting economic and education reforms to dealing with the country's crime and insecurity problems.
Hope, the analyst, said the protests will likely continue as long as there is no unimpeachable evidence that the remains belong to the students. Also unclear are questions such as why the gang members thought the students were rivals, and why they would have killed them even after learning that wasn't the case.
"We know the who, the what, the when and the where. We don't know the why," Hope said. "They have yet to tell a compelling story of why this happened. It doesn't matter how many people they detain — unless they answer that question, the whole thing will remain under a halo of mystery."