Lawyer Vidulfo Rosales reported that soldiers presumably involved in the disappearance of the students are already been interrogated.
The mothers of the missing students say that they are still alive.
They will hold a rally in the Monument to Benito Juárez.
The march, led by the parents of the missing students, began at the official residence of Los Pinos and is heading to the Zócalo.
They say that the creation of an investigation instance must be consulted with them.
The meeting between them and the President was also 'complex.'
The families of 43 missing students met with President Enrique Peña Nieto on Thursday and delivered a letter demanding a new internationally supervised investigation.
The meeting will be held on September 24.
They will continue with their protests.
They ask that the experts of the IACHR remain in the country indefinitely.