Maria Telumbre knows fire. She spends her days making tortillas over hot coals, and experience tells her a small goat takes at least four hours to cook. So she refuses to believe the government's explanation that gang thugs incinerated her son and 42 other missing college students in a giant pyre in less than a day, leaving almost nothing to identify the dead.

The discovery of charred teeth and bone fragments offer Telumbre no more proof of her son's death than the many graves unearthed in Guerrero state since the students disappeared Sept. 26. She simply does not accept that the ashes belong to her 19-year-old son and his classmates.

"How is it possible that in 15 hours they burned so many boys, put them in a bag and threw them into the river?" Telumbre says. "This is impossible. As parents, we don't believe it's them."

For the government of President Enrique Pena Nieto, the account, delivered by the attorney general and based on the confessions of detained gang members, begins to solve the mystery of the missing students. But for Telumbre, her husband, Clemente Rodriguez, and other parents, it is merely the latest lie from an administration that wants to quiet the poor and put this mess behind it. Their demands for the truth are fueling a pent-up national outrage at the government's inability to confront the brutality of drug cartels, corruption and impunity.

The Rodriguez family's chronicle of disbelief is rooted in collusion between Mexican officials and organized crime. The students of the Rural Normal School of Ayotzinapa were last seen in the custody of police in the city of Iguala, allegedly at the behest of the mayor. Soldiers and federal police didn't respond to the parents' urgent appeals for help. Federal officials waited 10 days before intervening. And when they did, parents say, authorities focused on finding graves rather than live students, so graves were all they found.

Telumbre and her husband say their beloved son, Christian Rodriguez Telumbre, is still alive, and they blame the government for failing to rescue him and his classmates.

"They are hidden somewhere," insists Clemente Rodriguez. "I hope that they're going to let them go any day now."

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Guerrero is a rough state with a history of armed uprisings and an economy fed by the production of heroin and marijuana. Far from the glitzy tourist resorts of Acapulco and Ixtapa, the Rodriguez family lives in a farming enclave near the teachers college in Ayotzinapa. Rodriguez delivers bottled water for a living, and Telumbre sells tortillas she makes on an outdoor stove. The smoke billows into their adobe house, a single room partitioned by curtains that is shared with their three daughters, Rodriguez's mother and, until recently, Christian.

Their son, also known as Lolo, wanted a higher education to help support the family. He had hoped to study agronomy at a university, but his parents didn't have the money. His only option was the tuition-free teachers college, known for spartan living and radical politics dating back to the Mexican Revolution.

He enrolled last summer but had not yet been allowed to take a class at the student-run school. Instead, upper classmen had put him and his first-year colleagues to work cleaning dorms, where they slept on mattresses on the floor, or planting crops and looking after farm animals. They also were required to take part in the school's fundraising activities, which can include taking over highway tollbooths and hijacking food trucks in the name of social justice, or commandeering buses to go to student demonstrations.

On Sept. 26, Telumbre and Rodriguez received a late-night call from their daughter alerting them to trouble and rushed to the school. There they were told that dozens of students had gone to Iguala to raise money, and police had attacked the buses they appropriated for the trip back. Details slowly trickled in: Christian had been part of the group; a student was shot in the head; three students and three bystanders were dead; one of the dead was found by a roadside with his face flayed and eyes gouged out.

Rodriguez set out for Iguala with about 10 parents. Their first stop was the federal prosecutor's office. Initially, guards denied them entry, but the desperate parents forced their way inside and demanded help. Officials said they had no information.

Then they went to Iguala police, who also said they knew nothing, though one suggested to Rodriguez that the radical students were criminals who might have gotten what was coming to them. It turned out federal authorities were holding a few students. They were released that evening and returned to school, but Christian wasn't among them.

Over three days, parents continued their desperate search in hospitals, at city hall and on the local military base. They chased leads that took them to dark caves and an abandoned hacienda where the students were rumored to be held by the Guerreros Unidos drug gang. In Iguala, Rodriguez pressed his mobile phone number into the hands of strangers and begged for anonymous tips, but everyone seemed scared to talk.

State officials arrested 22 Iguala police in connection with the bus shooting, and announced they were searching for 43 students. Mayor Jose Luis Abarca requested a leave of absence to make way for a full investigation, then went on the run with his wife, Maria Angeles Pineda.

Still, there was no news on Christian.

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Eight days after the students disappeared, federal officials announced more arrests. They said suspects had led them to hidden graves on a slope outside Iguala, near Pueblo Viejo. Twenty-eight bodies were discovered in the pits, but identification was complicated by a trampled crime scene and clumsy forensic investigators who dropped evidence in foul-smelling muck. The parents insisted they wouldn't find the boys there.

"We told ourselves not to be scared because it wasn't them," says Telumbre, 39.

"There's no scientific analysis where it says, 'Here are your boys.' We don't trust them," says her husband, 46.

Ten days after the students disappeared, President Pena Nieto weighed in and announced he would send federal security forces to "find out what happened and apply the full extent of the law." The Guerreros Unidos gang responded with a banner demanding the release of the 22 police officers in Iguala and warning of war.

Over time, 10,000 federal agents and dozens of forensics investigators in hazmat suits joined the search, and a reward of 1.5 million pesos (about $112,000) was offered for information on the missing students. More arrests were made — 76 in all. Still, no students.

Mexicans have grown accustomed to the discovery of mass graves with the detritus of narco wars, and the government says more than 22,000 Mexicans are missing as a result of organized crime and other violence. But the disappearance of the poor college students who had been detained by police struck a national nerve, and Mexicans were incredulous at the government's inability to find them.

Rodriguez joined a demonstration in Acapulco, and thousands of students marched in Mexico City demanding answers. Federal police took control of 13 municipalities in Guerrero.

On Oct. 22, Attorney General Jesus Murillo Karam announced that Iguala's mayor had ordered police to intercept the students so they wouldn't interrupt a speech being given by his wife, information prosecutors gleaned from a detained leader of Guerreros Unidos. The gang member said that the mayor's wife was "the main operator of criminal activities" in Iguala and that her husband received 2 million to 3 million pesos ($150,000 to $220,000) every few weeks in bribes for himself and his corrupt police force.

Under intense public pressure, Guerrero Gov. Angel Aguirre stepped down the next day.

Eventually, forensic experts found most of the bodies from the initial graves didn't belong to the students, though testing continues. Based on new arrests and confessions, the search moved to a gully below a garbage dump beside the San Juan River in the neighboring town of Cocula. Officials gave no details on what they were looking for.

The parents wanted more. They demanded a meeting with Pena Nieto and, on Oct. 30, finally managed to get an audience, during which the president promised a renewed search. As Rodriguez listened, his fury grew. Police had taken his son only a short distance from a military base in Iguala, yet soldiers did not intervene. "How is it possible that they didn't hear anything if they were there?" he asked the president. He said all the police in Iguala should be investigated. "Most should be locked up in prison."

A week later, federal police pulled the Iguala mayor and his wife out of their hiding place in a working-class neighborhood of Mexico City.

Finally, last Friday, Murillo Karam briefed the parents and then went on national television to give his detailed account of how the students were killed, based on interviews with suspects.

The boys were hauled to Cocula in dump trucks, so tightly packed that 15 died from suffocating on the way. The rest were killed there, the suspects said. The killers piled their bodies like cord wood on a pyre that burned for 15 hours, bagged the pulverized remains and tossed them into the river.

"The high level of degradation caused by the fire in the remains make it very difficult to extract the DNA that will allow identification," the attorney general said.

Nonetheless, he said, authorities were sending the ashes to a specialized laboratory in Austria in a last-ditch effort to produce the scientific analysis that would allow parents like Telumbre and Rodriguez to accept the death of their sons.

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The Rodriguez family home bears witness to the conflict within. It has been given over to an altar for Christian, with his photograph, a statue of a dark-skinned Jesus surrounded by prayer candles, yellow gladiolas and orange marigolds — Day of the Dead flowers.

Yet, Telumbre and Rodriguez hold fast to the belief that their son is alive. They show off photographs of a handsome young man with a wide smile who stands 6 feet tall, a giant in his family, towering over his partner in a folk dance troupe. They talk about closing off the street for the party they will throw for him when he comes home, and what a happy day that will be.

"Even though almost two months have passed, Murillo Karam says that they're dead, that the graves have been found, for me the boys are still alive," says Rodriguez.

In the weeks since the disappearances, public fury has swelled. Masked students and teachers march and chant daily, and some toss rocks and Molotov cocktails. This week, protesters shut down Acapulco airport for several hours and burned government buildings in Iguala and the state capital of Chilpancingo. Some protesters even set fire to a door of the National Palace in Mexico City.

Rodriguez's anger is growing, too. He says the parents must "do whatever it takes" to keep pressure on the government. He blames the school that sent the boys into danger to collect funds, the mayor and police of Iguala who worked with gangsters to disappear them, the governor of Guerrero and the attorney general who have failed to find them, and Pena Nieto.

"If it were his son, he would move sea and land to find him," Rodriguez said. "But since we're poor people, they humiliate us, discriminate against us, crush us."

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Associated Press writers Mark Stevenson and Jacobo G. Garcia in Tixtla contributed to this report.