Attorney General Jesus Murillo Karam Wednesday said at a press conference that the mayor, Jose Luis Abarca, ordered police to attack the students to prevent them from disrupting an event in which his wife, head of the local family services office, was to give a speech.
His remarks to the press came on a day when thousands of students, teachers and civil society members marched in numerous cities across Mexico to demand that authorities get to the bottom of the case of the missing students.
One of the biggest marches took place in the city of Iguala.
After last Friday's arrest of the leader of the Guerreros Unidos cartel, Sidronio Casarrubias, authorities learnt that the Iguala mayor's office was completely infiltrated by organised crime and received between 2-3 million pesos (between $148,000-$222,000) a month from the drug mob.
The local police were also controlled by organised crime, with at least 600,000 pesos ($44,500) being spent on a monthly basis to pay corrupt cops.
Murillo also said that a total of 30 bodies have been found in nine clandestine graves.
But it has not been confirmed whether the bodies are those of the missing students, Murillo added.