MEXICO CITY (Reuters) - Mexican officials have begun scouring new sites for the remains of 43 student teachers who disappeared five years ago, after authorities said they would start the investigation from scratch, having discarded the results of a previous one.

People march to mark the fifth year since the disappearance of the 43 students of the Ayotzinapa Teacher Training College in the state of Guerrero, in Mexico City, Mexico September 26, 2019. REUTERS/Carlos Jasso

The abduction and apparent massacre of the youths, widely believed to have been committed by corrupt police working with a violent drug gang on the night of Sept. 26, 2014, drew international outrage and condemnation of the administration of former President Enrique Pena Nieto.

Pressure has been growing on Pena Nieto’s successor, President Andres Manuel Lopez Obrador, to fulfill his promises to uncover what really happened in a case that many Mexicans link to federal authorities.

In a sign of continuing outrage over the case, thousands of people filled the capital’s vast main square on Thursday, to mark the anniversary with a mostly peaceful march, though scattered incidents of vandalism were reported along the route.

One place being searched is a garbage dump in Tepecoacuilco, a few miles from the southwestern city of Iguala in Guerrero state where the student teachers were abducted.

Mexico’s undersecretary for human rights, Alejandro Encinas, spoke of the site in comments to reporters at a regular news conference on Thursday flanked by Lopez Obrador.

Both men and other officials shed their usual suits for T-shirts emblazoned with the number 43 to commemorate Thursday’s anniversary of the students’ disappearance.

Encinas said the armed forces, the attorney general’s office and members of a presidential commission were all taking part in the search at the dump, which started last weekend. Searches carried out in other sites over the past few weeks have not turned up remains of the students, he said.

“We are convinced that in the Ayotzinapa case, the only truth until now is that there is no truth,” said Encinas. Ayotzinapa is where the students’ all-male college is located.

Slideshow ( 26 images )

A special prosecutor appointed to oversee the re-examination of the case said last week that authorities would virtually “start from scratch” after previous mishandling of the case.

The lack of progress was brought into focus earlier this month when a judge ordered the release of Gildardo Lopez Astudillo, a gang leader blamed for ordering the killing of the students.

The government on Thursday reiterated an offer of rewards of 1,500,000 pesos ($76,000) per student for any credible information about the case.

PROBE ‘DISCREDITED’

Lopez Obrador took office in December pledging to pursue the Ayotzinapa investigation. His government has described the original probe as “discredited” and vowed to go after the officials who led it.

Officials said they would call Jesus Murillo, the attorney general who oversaw the Pena Nieto-era probe into the disappearances, to answer questions about it next week.

Angela Buitrago, a consultant named by the Inter-American Commission on Human Rights who is helping to oversee the new probe, said it could not advance without investigating military officials who were present in Iguala five years ago.

Lopez Obrador said in December that military officials should be put under scrutiny in relation to the case, but it is not clear how that aspect of the probe has advanced so far.

According to the Pena Nieto administration, local drug gang Guerreros Unidos mistook the students for members of a rival outfit, killed them, incinerated their bodies in a nearby garbage dump and tipped their remains into a river.

However, the remains of only one of the 43 was ever definitively identified, and a group of independent experts later picked several holes in the official version of events presented in 2015.

The United Nations human rights office said in a report last year that it appeared Mexican authorities had tortured dozens of people during the investigation. Out of 142 suspects detained in the case, more than half have been released.