Night is the most difficult time at the rural teachers college, where families have stayed on thin, bare mattresses in classrooms since 43 students went missing a month ago. The day's distractions of meals, meetings and marches end, and the parents are left with their thoughts, questions and a simmering rage.

Sleep has eluded Clemente Rodriguez Moreno, 46, since his 19-year-old son Christian disappeared with his classmates. Each night Rodriguez returns to his home close to the Raul Isidro Burgos school in Tixtla and his mind races.

"What will come of them? We don't know if he's eating, if he's injured, if they're hitting him."

The families' lives have been upended since police in the town of Iguala, allegedly on the mayor's orders, attacked the students to stop them from interrupting a speech by the mayor's wife on Sept. 26. Both the mayor and his wife are fugitives, along with the police chief.

Three students, including one later found with the skin peeled off his face, and three people unrelated to the attack, died in a series of initial attacks. Investigators say the rest of the students were driven off to a police station, later turned over to the drug gang Guerreros Unidos and have not been heard from since.

Everything since has been a nightmare, said a 57-year-old farmer from Ayutla who spoke on condition of anonymity as a precaution against reprisals. He walks his 19-year-old son's campus in the Ayotzinapa neighborhood in a daze.

"I don't sleep for the thinking," he said, fingering a foil packet of sleeping pills prescribed by a doctor who came by to help. "I don't feel like I'm living life."

His family has few resources, he said, and his son came to the school because the students support themselves. That's what he said they were doing that afternoon in Iguala, soliciting donations.

Staring at the photograph of his son after a march to demand the return of the missing, the farmer spoke one moment of the anguish of not knowing. His eyes welled with tears and he bit his lower lip. Next flashed an anger that has been building over weeks. He said he's tired of a corrupt government that has always scorned poor farmers. He wants the guilty to pay.

"If they don't give them to us, we'll have to proceed another way, with more resistance," he said.

There was so much confusion in those early days, said Valentin Cornelio Gonzalez, a 30-year old farmer from the municipality of Tecoanapa who dropped everything to travel to the school, where his brother-in-law, 19-year-old Abel Garcia Hernandez, is enrolled. Was the attack at the school or in Iguala? Were the attackers police or cartel gunmen? How many students were missing?

Some gaps have since been filled, but the gaping one, the one families care most about, remains a void, despite the arrest and interrogation of more than 50 suspects. So Gonzalez, clad in well-worn leather sandals, has been marching — in the state capital of Chilpancingo, in Acapulco, in Mexico City — demanding an answer. When he first arrived at the school he and other relatives spent a fruitless day searching around Iguala. They feared for their safety, but fault the government for not doing enough: "They're not looking for them like they should."

As other searchers turn up more and more gravesites in the mountains around Iguala, the families can only wait to hear if the DNA samples they gave weeks ago match or if the remains are the loved one of some other desperate family.

Mario Cesar Gonzalez, 49, the father of 21-year-old Cesar Manuel Gonzalez Hernandez, spends his days at the school pacing in cowboy boots. He's boiling too much inside to sit for a massage or take lessons in meditation techniques offered by others who want to help. He can't stand with the other parents before the makeshift altar in the middle of the school's basketball court to sing a hymn. One minute he's listening in a small circle of parents on the basketball court and the next he's walking away, his cell phone held tight to one ear and a cigarette between his fingers.

He's so proud of his son. Even after weeks without news of their whereabouts, Gonzalez and other parents unfailingly speak of their children in the present tense. Cesar wants to fight for the poor, he said.

Cesar told his mother he would help her so she could leave the department store job that exhausts her. The young man doesn't know that after a month of living at his school and waiting for his return, his mother has lost her job. So has his father, who worked at a body shop in Huamantla.

"That doesn't matter to me anymore," Gonzalez said.

Clemente Rodriguez left his chickens, geese and pigs, as well his work delivering water jugs, to spend four days last week in Mexico City collecting donations for the school, marching and telling his story over and over.

Sporting cowboy boots and an Angry Birds baseball cap, Rodriguez boasted that his son stands over six feet tall and loves to folk dance.

He's focusing more on immediate tasks rather than the increasingly likely scenario that no parent wants to consider.

"I don't despair," said Rodriguez, "because my heart is telling me the students are alive."