Parents of the students see the resignation of Tomás Zerón as an empty gesture since he's being rewarded with another high-level government job.
The violence began when armed men attacked a hotel that was housing federal police officers sent to reinforce security in the latest of many special law enforcement offensives that have failed to bring peace to the once-glamorous resort city.
The national human rights commission says it has a credible witness who saw and heard federal police agents okay the abduction of between 15 and 20 of the students.
The tortilla industry in the beleaguered state of Guerrero is under attack from local cartels that are kidnapping and killing business owners and workers, as well as using tortilla shops as drug distribution points and lookout posts.
The Argentine Forensic Anthropology Team found no evidence of the kind of fire required to support the government's earlier conclusion that the students were incinerated at a garbage dump. This is the second external study to demolish that version.
Over 70 mayors have been killed over the last ten years in Mexico but while many have been rumored to have made deals with criminal groups, Gisela Mota enjoyed a clean reputation.
Drug lord Chapo Guzmán's escape from a maximum-security prison overshadowed the arrest of other capos and underlined how few new ideas the government has brought to the fight against Mexico's cartels.
The wave of armed attacks, abductions and general violence in the last couple of weeks highlights the failure of multiple security operations in the last year.
Edgar Valdez Villareal became a somewhat larger-than-life figure after his arrest in 2010 when he smirked before news cameras and boasted that a movie would be made about his life in the drug world.
Tens of thousands of protesters march in Mexico City on rainy day to show indignation over the missing students remains strong
The parents met with President Enrique Peña Nieto with emotions running high, two days ahead of the first anniversary of the disappearance of their children.
The meeting comes two days before the first anniversary of the police attacks on the students that also killed six people. Parents also began a 43-hour fast on Wednesday.