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A mixture of anger, disappointment and defiance against the government dominates the national mood while Mexico prepares for Saturday's national day of protest marking the one-year anniversary of the disappearance of 43 teachers’ college students in Iguala, Guerrero, last year.

Thursday afternoon, parents of the missing students were greeted by supporters with the now familiar rallying cry “Alive they took them, we want them back alive!,” as they returned from their second meeting with president Enrique Peña Nieto to a white tent on the central Zócalo square in Mexico City, which is serving as their temporary lodging.

But instead of defiant, the parents seemed despondent. They addressed the press and their supporters and once again expressed their disappointment with Peña Nieto's apparent lack of commitment to solving the disappearance of their children.

“It's clear that he's waiting for this movement to become weary and forgotten,” Felipe de la Cruz, spokesman for the families, said. “The insensitivity of this man has overtaken his human feeling, and we condemn his attitude.”

The families began a symbolic 43-hour hunger strike on Wednesday evening. During yesterday's meeting, they presented eight new demands, including that the federal government allow a special unit to search for the students under international supervision.

Instead, the president offered to set up a special prosecutor's office to handle the case, much to the chagrin of the families, who feel federal institutions have repeatedly failed to make any progress in the search for the missing youths.

Nationwide anger over what some organizations have called one of the greatest human rights tragedy's in Mexico's recent history flared up again this month, after investigators of the Inter-American Commission on Human Rights (IACHR) concluded on Sept. 6 that a federal investigation into the disappearance was deeply flawed.

The students were attacked by local police on the night of Sept. 26 last year, as they crossed Iguala in buses that they had hijacked in order to get to a protest against educational reform.

According to the official explanation the government holds to, the students were taken into custody by local police and handed over to members of a local drug trafficking gang, who killed them and incinerated their bodies at a garbage dump.

More than a hundred people have been arrested on suspicion of involvement in the event, including dozens of municipal policemen, Iguala's mayor, who allegedly ordered the abductions, and the latter's wife.

But the IACHR concluded that it was physically impossible for the alleged killers to have disposed of the bodies by burning them. They determined, after 6 months of investigation, that the timeframe involved was too short and the amount of fuel needed for the pyre impossibly big.

Moreover, recent media reports suggest some of the witnesses upon whose statements the federal government based its official version were tortured.

In Guerrero, the IACHR's report led earlier this week to violent clashes between riot police and students at Raúl Isidro Burgos college – commonly known as Ayotzinapa, the school the 43 attended.

On Thursday, hundreds of policemen sealed off the two main access roads to Tixtla, the town where the college is located, to prevent students from travelling to Mexico City to participate in the protest march scheduled for Saturday.

Members of Mexico's Chamber of Deputies, meanwhile, got into heated discussions and even a fistfight while debating the IACHR report.

The disappearance of the Ayotzinapa students is but one of many recent crises the Peña Nieto administration has had to face. The president's approval rating has dropped sharply amidst rising poverty and drug violence, a sluggish economy and an explosion of violence against journalists – not to mention the prison escape of Sinaloa Cartel  kingpin Joaquín “El Chapo” Guzmán's in July.

This year's traditional presidential “Independence Shout” – when Mexico’s president appears on a balcony of the National Palace overlooking the Zócalo rings a bell and shouts out patriotic messages – was received by a relatively small crowd with only a lukewarm reception.

According to media reports, a fair amount of the assembled crowd was trucked in from nearby towns and cities loyal to the ruling Institutional Revolutionary Party (PRI).

In contrast, many thousands are expected to participate in the protest march marking the disappearance of the Ayotzinapa students.

“We ask all Mexicans who feel indignation to head out to the street this Saturday,” de la Cruz, the spokesman for their families, said. “If we keep silent today and stay hidden, history will repeat itself soon.”

Human-rights activists such as Heriberto Paredes, who also works as an investigative reporter for the website Subversiones, say the IAHCR’s recent revelations helped regain the momentum the missing students' parents and their supporters had in public opinion early this year.

“For a while, there had been a certain calm with regard to the marches and acts of protests by the families,” Paredes told Fox News Latino. “Things are heating up again, however, now that the official investigation has been discredited.”