By Anahi Rama and Lizbeth Diaz
IGUALA, Mexico(Reuters) - Terrorized by brutal drug gangs and corrupt police, residents around this town in southwestern Mexico have for years kept silent when relatives disappeared, fearing they would be targeted next if they made a fuss.
Some tried their own low-profile searches, even going to spots where they saw vultures circling above, but most kept quiet and others simply fled the area when they were threatened.
Then, 10 weeks ago, 43 trainee teachers were abducted by police in Iguala and handed over to hitmen from a local gang which the government says murdered and incinerated them.
A groundswell of outrage has since swept Mexico with hundreds of thousands of protesters taking to the streets to demand action from a government that has failed to halt the bloodshed or tackle rampant corruption.
In Iguala, the anger is palpable. But something else is happening, too: families of other victims are taking advantage of the sudden arrival of federal police and army troops to go out and search for their missing.
Relatives and friends of around 300 people who since 2008 have "disappeared" - often a euphemism for kidnapped and murdered - have taken up shovels and picks to search for clandestine graves in the hills around the town, a hive of opium and marijuana trafficking.
"The disappearance of the students was the trigger. Many people are still scared but we have to break it for things to change," said Citlali Miranda, a psychologist who is organizing a group of relatives and searching for two of her own cousins.
The group has so far found 16 sets of suspected human remains at sites located via anonymous tip-offs and have handed them over to the attorney general's office for DNA checks.
Alongside them, investigators who descended on Iguala to look for the missing students have themselves found a series of mass graves containing the remains of 39 bodies.
Not one of them belonged to the trainee teachers.
Luis Manuel Munoz, a 62-year-old retiree, sat in a church courtyard as families gathered to plan their searches and described the misery of not knowing what happened to his son Cuauhtemoc, a young soldier who went missing in 2010.
"You go to sleep and wake up, expecting your child to be there, but then the bitterness of not knowing where he is comes back," said Munoz, who has already seen too much violence in this corner of Guerrero state, where town halls and police departments have long been infiltrated by drug cartels.
One of his nephews was found dead in 2009, his face ripped off in the hallmark of a gangland killing, and the dismembered remains of an acquaintance were dumped by a roadside in 2010.
"It's in all of the country, not just here. Mexico is living through something really horrible," he said.
There have been countless atrocities across Mexico since the drugs war exploded in 2007 but the massacre in Iguala has triggered more outrage than any other.
President Enrique Pena Nieto, who spent his first two years in power pushing through economic reforms aimed at attracting foreign investors, has been forced to turn his attention to law and order.
"The shameful events in Iguala have shown that Mexico is stuck in a state of affairs which is unacceptable and must be overcome," he said last week as he unveiled a series of measures to improve policing.
The task ahead is huge and Pena Nieto, also caught up in a conflict-of-interest scandal, looks weak. His approval rating has plummeted.
More than 100,000 people have been killed in gang-related violence since 2007 and around 22,000 others have disappeared. About 92 percent of crimes go unreported, and widespread impunity and corruption fuels the violence.
The murder rate in Guerrero state, home to Iguala and the beach resort of Acapulco, doubled between 2008 and 2013 to hit 63 per 100,000 inhabitants - about 13 times the U.S. rate.
Attorney General Jesus Murillo said Iguala's former mayor and his wife were the probable masterminds of the students' disappearance. They are among more than 70 suspects, including dozens of police, held in connection with the case.
At least 12 other mayors are under investigation for suspected links to organized crime in Guerrero alone.
Many Mexicans are skeptical about the government's account of what happened to the students and Pena Nieto's ruling party has for decades been infamous for corruption.
There is also growing evidence of ties between organized crime and opposition politicians. In parts of Mexico, including areas on the U.S. border, the gangs have almost total control.
Recruiting youths in impoverished areas to work as hired killers for as little as $300 a month, the cartels often bankroll the campaigns of local politicians.
So for relatives of those killed, Pena Nieto's promise of security reforms rings hollow.
"If the government had acted earlier ... what happened would have been avoided, not just in Iguala but all over," said farmer Nardo Flores, whose son is among the 43 missing students. "So many people have disappeared."
(Editing by Simon Gardner, Dave Graham and Kieran Murray)