Officials say they’re ‘rethinking’ past probes as search for the 43 students who went missing 5 years ago continues.

Mexico City – Mexican officials on Thursday said prosecutors are exploring new lines of investigation ignored by the previous administration in order to solve the case of the 43 missing students from a rural teacher’s college in Ayotzinapa who disappeared five years ago while under police custody.

The case was effectively closed during the previous administration, plunging Enrique Pena Nieto’s administration into a crisis after human rights groups, international organisations and journalists denounced a series of contradictions, obstruction of justice and cover-ups pointing to forced disappearances.

The official account – known as the “historical truth” – said that local police officers surrendered the students to members of a drug gang linked with the town’s mayor, who had confused them with members of a rival gang and killed them, later burning their bodies in a rubbish dump and throwing the ashes inside garbage bags into a river.

But independent investigations later suggested the case was heavily based in confessions of alleged criminals obtained under torture. The remains of only one student were found in the dumpster and river.

President Andres Manuel Lopez Obrador reopened the case soon after he was elected last year. During his daily news conference on Thursday, Lopez Obrador and his team addressed reporters and the students’ families and briefed them on the new investigation developments.

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“We will make a comprehensive rethinking of the investigation, correcting the omissions, contradictions, and the lack of evidence that led to the so-called ‘historical truth’,” said Alejandro Encinas, Mexico‘s undersecretary of human rights who is overseeing the commission investigating the case.

“And those authorities that incurred in omission or illegal practices, as has been proven … such as torture on some of the people detained, will be held responsible,” he added.

In this handout photo released by Mexico’s presidential press office, Mexican President Andres Manuel Lopez Obrador speaks at a news conference at the National Palace in Mexico City [Handout/Mexico’s Presidential Press Office/AFP]

The government officials, including the president, wore commemorative grey T-shirts with the number 43 instead of their usual suits at the news conference.

The progress laid out by officials included the creation of new commissions, the offering of monetary rewards for information on key suspects and the identification of “critical” phone calls “during and after the fact” that eliminated any suspicions that the students had any contact with criminal gang members. Investigators also began conducting searches new locations, officials said.

“The truth is that so far there’s no truth,” said Encinas.

‘We will continue until the case is solved’

Parents and family members travelled to Mexico City on Thursday and spoke at a congress hearing demanding new investigations include the army among other state actors. They also held a mass in memorial of their missing children. Thousands also rallied to demand justice.

“I do feel things are progressing, slowly, but progressing,” said Omar Garcia Velasquez, a former a spokesman for the 43 missing students’ movement who said he is one of the students who survived the police attacks that night five years ago.

“I understand it’s very complicated to start from scratch, and I know the narrative has changed towards the victims and their families; parents are being treated better,” Garcia told Al Jazeera. “But nevertheless, we will continue with our movement until the case is solved.”

People hold up posters during a march to mark the fifth year since the disappearance of the 43 students of the Ayotzinapa Teacher Training College in the state of Guerrero [Carlos Jasso/Reuters]

Pressure has been growing on Lopez Obrador to fulfil his promise to uncover the truth of what really happened with the missing students.

Many Mexicans were outraged after more than half of the 142 suspects arrested during Pena Nieto’s administrations were freed because of case irregularities.

“We’re concerned about how some of these detainees have been released because it means the investigations were indeed plagued with irregularities,” said Erika Garcia Guevara, Americas Director at Amnesty International.

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“We’re hoping the attorney general will not only get to the bottom of what happened with the students, but also find out who were the authorities responsible for these irregular investigations and possibly even for concealing evidence,” she told Al Jazeera.

In 2014 an independent experts group, called GIEI, was created to collaborate with the Mexican government to investigate the Ayotzinapa case. The GIEI reported many contradictions and irregularities in how the previous case was conducted, and issued recommendations to pursue new lines of investigation.

Mexican Senator Emilio Alvarez Icaza was the former president of the Inter-American Commission on Human Rights when the GIEI was created.

“It’s important that the president sends out a clear message that the army will be investigated,” said Alvarez Icaza.

“Because without it and the increasing militarisation we’re seeing in the country, the message will be that the army is untouchable,” he told Al Jazeera.

“This is a case where the credibility and trust of Lopez Obrador’s government are at stake, he said. “If this story also ends up in impunity, the public’s outcry will be enormous.”