MONTERREY, Mexico -- Rosa González cannot shake the memory of the state investigator who was too afraid of reprisals to take a full report, the police officer who shrugged when the ransom demand came, the months of agonizing doubt and, most of all, the final words from her daughter before she disappeared.
"I am giving you a hug because I love you so much," her mentally disabled daughter, Brizeida, 23, told Rosa hours before she was abducted with her 21-year-old cousin after a party more than two years ago.
In thousands upon thousands of cases, the story may well have ended there, adding to the vast number of Mexicans who have disappeared. Unlike those in other Latin American countries who were victims of repressive governments, many of Mexico's disappeared are casualties of the organized-crime and drug violence that has convulsed this nation for years.
But here in Nuevo León State, prosecutors, detectives, human rights workers and families are poring over cases together and in several instances cracking them, overcoming the thick walls of mistrust between civilians and the authorities to do the basic police work that is so often missing in this country, leaving countless crimes unsolved and unpunished.
About 26,000 missing-person reports sit in the federal government's database, everything from drug-related abductions to runaways, and the administration of President Enrique Peña Nieto, who took office in December, has promised to do more to find out what happened.
Often, that would require the authorities to investigate themselves. This month, the national human rights commission said it was looking into 2,443 cases in which the police or military, corrupted by criminal gangs, appeared to be the abductors.
But public pressure from victims' families and international groups has been mounting, repeatedly condemning the widespread failure to investigate the scourge of disappearances. After a series of protests by mothers of victims at the federal attorney general's office in Mexico City, it announced two weeks ago that a unit was being assembled to delve into the cases.
"We are not doing magic," the attorney general, Jesús Murillo Karam, told reporters at the announcement. "We are going to get as far as you can. We are going to exhaust all the options and speak with absolute truth about the possibility of results."
Advocates for the victims remain skeptical, saying the real work needs to be done at the state and local level, where the cases are first reported and most investigators and leads reside.
Here in Nuevo León, one of the states hardest hit by violence, they have praised the prosecutor's office for working with a local human rights group and family members to review several dozen cases, sometimes performing investigations that were never done in the first place.
Another look at Ms. González's case last year helped lead the police to a gang leader who was arrested in January. He confessed to abducting and killing the women, and directed the authorities to the remains of the cousin; further testing of bones at the site is under way to determine if any belong to Ms. González's daughter. "Whatever God may want," Ms. González said through tears, "whether my daughter is alive or dead, I am resigned to whatever may come."
Since agreeing in June 2011 to reopen dozens of cases, out of thousands here in the past several years, the authorities and their civilian counterparts have met monthly to go over leads and any progress made on them. Fifty-two cases have been resolved, with some people found dead and others alive, including 12 this year who were discovered to be in the custody of the authorities, unknown to their families. About 40 people have been arrested on abduction or homicide charges, 16 of them police officers.
"Nuevo León is one of the only states where you see prosecutors actually doing the due diligence of conducting investigations, meeting with families, going to the crime scene, taking common-sense steps to advance the investigation," said Nik Steinberg, an investigator with Human Rights Watch, which in February published a damning report on the disappeared. "To search for the missing and find the people responsible for taking them, in Mexico where normally investigators don't do any of that, that is progress."
Mexico has only a rough sense of how many people have disappeared amid a surge of violence over the past several years that has left tens of thousands dead in battles between drug gangs, organized-crime groups, the police and the military.
Sometimes people vanish en masse; a dozen young people, two of them sons of convicted drug dealers, were kidnapped from a Mexico City bar last month and have not been found.
The federal government's huge database of missing-person reports was compiled by the previous government, and last month the new interior secretary said the list was being combed through, expressing confidence that many cases were not abductions or the result of foul play, but rather more mundane instances of people leaving home and moving to new places, including the United States.
Still, many others are cold cases, with little forensic evidence to go on, witnesses who refuse to testify and concerted efforts by criminal gangs to do away with the bodies.
Maximina Hernández has been looking for six years for her son, José Lara Hernández, a police officer from a Monterrey suburb who apparently was intercepted on his way home from work and abducted by men in a sport utility vehicle. A witness saw the whole episode but refuses to give details to investigators, out of fear or possible involvement in the crime, she said.
"I don't want to go against anybody," she said. "I just want to know where my son is."
Eduardo Ayala, who helps coordinate the investigations at the Nuevo León prosecutor's office, acknowledged the challenge of the cases but said the authorities were making headway, in part because the state had fired about two-thirds of its police forces in a mass cleanup of corruption begun in 2011. "There is much left to do, but we are moving ahead," he said. "The police now go to every corner of the state to investigate where they did not before."
He said the state, working with the United Nations and experts from other countries, is writing a protocol to standardize how such cases should be handled.
Much of the impetus has come from Consuelo Morales, a Catholic nun who directs a local human rights organization known as Cadhac.
"We have a checklist," she said. "Did they take a DNA sample, did they get cellphone records, if there was a license plate number of the car that took the victim did they check that?" Ms. Morales said that in many cases, initially, the answers were often no.
Ms. González, after chasing rumors that her daughter had been spotted in several other cities, took her case to Ms. Morales last November, two years after the abduction. They met with prosecutors and tracked down the case file, filling in details left out before and cross-matching it with current investigations.
The police were building a separate case against Jaime Cabello Figueroa, 40, an organized-crime boss who operated in the town where the women were seized. When he was detained in January, the police said he confessed to or was implicated in several killings and disappearances, including the case of Ms. González's daughter and the cousin.
Ms. González now wants to speak directly to him, so he can see her pain and offer more information on her daughter. She said she had paid a ransom, but then contact with the captors ceased. The police never followed up, making her wonder if some were involved.
"They told me if I walk into that jail and talk to him, the bad guys will have eyes on me and have me followed outside," she said. "But if they are going to kill me, they are going to kill me. I am fighting for my daughter to be found, wherever she is."
This article originally appeared in The New York Times.