Mexico City, January 27 (RHC-teleSUR) -- Once again, the parents of the disappeared 43 students from the Ayotzinapa teacher's training college lead several marches and actions in the Mexican capital to mark four months since their children were attacked and forcibly disappeared by police in Iguala, Guerrero in late September.

Accompanied by dozens of social organizations, unions, student groups and thousands of citizens, the parents lead four strategic marches early on Monday morning, essentially shutting down the city center to vehicular traffic.

The families of the missing students and their classmates maintain harsh criticism of the authorities and their investigation thus far in the case. They believe the government seeks to quickly close the investigation and discredit the voice of the families of the victims.

Although nearly 100 people have been detained in connection to the disappearance and possible mass murder of the students, little concrete scientific evidence has emerged to substantiate testimonies and confessions gathered by authorities from the Attorney General's office (PGR).

The PGR maintains that the students were handed over by Iguala police to the organized crime group Guerreros Unidos, who in turn executed the youths and burned their bodies. The authorities affirm that 17 charred human remains were found not far from a garbage dump in the community of Cocula.

However DNA testing confirmed the identity of only one bone fragment as belonging to Ayotzinapa student Alexander Mora. According to forensic experts in the University of Insbruck, Austria, the DNA of the other remains is nearly impossible to identify.

The Argentine Forensic Anthropology Team, contracted to be an independent party to analyze the physical evidence in the case has warned that it cannot independently verify the location where the PGR recovered the charred remains in question.

These doubts over the physical evidence have caused the families and classmates of the students as well as social organizations to open-up other lines of investigation.

Earlier this month, after mounting social pressure, Mexico's Interior Minister, Miguel Angel Osorio Chong, agreed to open up certain military installations to be investigated and examined, however the date and logistics have not been confirmed.