“The issue of organized crime and its penetration into institutions isn’t just the heritage of Iguala,” he said. “It’s broader, it’s more extensive — in Guerrero and the country.”

The federal government has tried to put the case of the missing students to rest. Attorney General Jesús Murillo Karam has said that confessions and physical evidence have confirmed that the students were detained by Iguala police officers on the orders of its mayor, José Luis Abarca, and handed over to members of the Guerreros Unidos drug gang, who killed the young men and then burned their bodies.

The same day the government declared that the students were dead, President Enrique Peña Nieto said that Mexico “must advance with greater optimism.”

But few here believe Guerrero will move on.

“Guerrero’s disgrace is that there are many Abarcas,” said Mr. Ortega, a university professor appointed after the previous governor stepped down in October, discredited by his ties to Mr. Abarca.

At the center of the tumult are the families of the students, all young men, who wait at the college’s bare-bones campus in the village of Ayotzinapa, a 20-minute drive from the state capital here. Mothers sit embroidering under the shade of an arched metal roof over a basketball court as though sheer tenacity will conjure their sons’ return.

The government is trying “to stop the families from mobilizing,” said Melitón Ortega, the father of Mauricio Ortega, 17, a missing first-year student. “They want us to resign ourselves,” he said. “We say ‘no.’ Until they identify them, we want them to look for the students alive.”

Last week, an expert Argentine forensic team following the case for the families raised questions about the government’s conclusion, pointing to inaccurate DNA testing and the failure to guard the site where the government says the young men were killed. On Monday, Mr. Murillo Karam’s office defended its investigation and shot back that it was “not acceptable” to “try to sow doubt.”