Almost 18, Laura Berenice Monarrez was a serious student with dreams of a big future. She wanted to be a medical examiner, she told her mother in a long conversation on Sept. 18, 2001. Boys were just a distraction from her career plans, she said.

Three days later, "Bere" Monarrez disappeared. Seven weeks after that, her body and those of seven other pretty young women were found in an abandoned cotton field beside a busy boulevard near downtown. All had been raped and strangled.

Today the so-called campo algodonero or "cotton field" case remains unsolved, as do many of the 377 slayings of women and girls over the past 12 years in this gritty, industrial border city.

"For us, four years have passed and we have a lot of programs, but we have no justice," said Benita Monarrez, 43. Although government funds have been established to compensate families of murder victims, she said, the money means nothing as long as her daughter's killer remains at large. "For me, that is injustice."

For years, the mysterious deaths and disappearances of women have frustrated officials and terrified families in Juarez, a transient city where thousands of women live in shantytowns and work in maquiladoras, the factories on the U.S. border that produce electronic circuit boards and auto parts.

About a fourth of the victims were kidnapped, raped and strangled in a similar way, leading victims' families to believe that a sexual serial killer remains on the loose. The whereabouts of almost 40 other women who have disappeared since 1993 are still unknown. And this year, the number of homicides with female victims has surged to 30, although authorities attribute 80 percent of them to domestic or family violence.

More than 100 of the murder cases remain unsolved because of bungling by inept or corrupt officials, according to investigations by the United Nations, Amnesty International, the Inter-American Human Rights Commission and other groups. Mexican federal officials have conceded negligence due to lack of resources and investigative or technical skills.

Maria Lopez Urbina, the first appointed federal special prosecutor for the city of Juarez, was even more accusatory. This summer, as Urbina prepared to leave the post, she said some murders might never be solved because of "incorrect, negligent or outright omissive" conduct by about 130 officials in previous prosecutors' offices in Chihuahua state.

Now, a new set of state officials is trying to bring justice to the families of slain women and reform the state's criminal justice system.

"We are working to change the mentality and eradicate the corruption and the impunity that has permeated the state," said Patricia Gonzalez Rodriguez, a former criminal court judge who was appointed attorney general a year ago by Chihuahua's governor, Jose Reyes Baeza.

This year, Gonzalez has reopened 140 unsolved cases of murdered women, dating to 1993, and has made some arrests. The most notable was that of Jose Luis Hernandez Flores in the 1998 abduction, rape and murder of a woman whose family had insisted to police for seven years that they suspected Hernandez, among others.

Gonzalez's office has also fired more than 30 state officials, including lawyers and investigators, and brought administrative charges of abuse of authority against them for mishandling the murder cases. Criminal cases have been filed against six.

Pressured by the international human rights community, which has kept a spotlight on the Juarez murders, Gonzalez agreed to hire a team of forensic anthropologists from Argentina to help identify the women found here and in the provincial capital. The team, which investigates human rights violations worldwide, this fall has examined 54 bodies, including 24 exhumed from mass graves where they were placed as desconocidas, or unknown women.

With the help of $5 million in U.S. aid, Gonzalez's office also has established a project to train police and prosecutors in criminal investigative procedures and accountability, and to help shift the state to a system of open, oral criminal trials. Currently, criminal courts in Mexico are closed to the public and depend upon written statements submitted to a judge -- a system that human rights groups say lacks due process and is highly vulnerable to corruption.

Some murder suspects are believed to have been framed as scapegoats and remain in jail, including the cousin of a girl from Chihuahua who was killed in May 2003, thousands of miles from where the cousin lived.

But some attempts have been made to rectify such abuses by the criminal justice system. One was the dismissal of charges against Victor Javier Garcia Uribe, who had been convicted in the campo algodonero murders and sentenced to 50 years in prison.

Garcia was convicted of being a serial murderer despite evidence that he had been tortured into confessing, testimony from a forensics expert that he was ordered to plant false evidence and witnesses who said police threatened them into giving false statements.

In June, Garcia's case was thrown out by the State Supreme Court for lack of evidence. He was released after 31/2 years in prison, where his co-defendant, Gustavo Gonzalez Mesa, died in 2003 following a routine medical operation. One of their attorneys was killed by Juarez police in 2002.

"Our obligation now is to look at the leads that four mothers have given us," Gonzalez said. "They had previously presented that information but had been ignored."

She said her office, as well as that of the deputy attorney general in charge of Juarez prosecutions, has been trying to establish relationships with victims' families. But after years of disregard, neglect and coverups, winning their trust will be a difficult task, other experts said.

"These families are very, very damaged and must be treated very gently," said Mercedes Doretti, one of the Argentine forensic anthropologists who has been reconstructing investigative files, collecting DNA samples and working with dozens of families. "They really believe that because they are among the poorest, and have the least means, that nobody cares about them," she said.

This month, those samples and pieces of bones from 54 cadavers were sent to a laboratory in Virginia that analyzed the DNA of the remains of the victims of the Sept. 11, 2001, terrorist attacks.

In a recent report, the Washington Office on Latin America, a human rights group, said that hiring the forensic experts was a positive change from the "shortcomings" in Mexico's efforts to solve the Juarez and Chihuahua murders. The report called it "an important step in alleviating families' anguish and uncertainty" and "guaranteeing their rights to truth and justice."

For Benita Monarrez, the path to justice for her daughter's murder has been fraught with agony and grief. Four years ago, when the eight bodies were found at the campo algodonero, she said she was not allowed to view the corpses and make a positive identification. The authorities, she recounted, said they were convinced by information she had provided that one of the bodies was her daughter and that they wanted to protect her from the awful sight.

Later, Monarrez said, she begged to be given her daughter's remains and finally received them in March 2002. By then, however, all that was left was a bag of bones, suggesting how carelessly officials had preserved them.

Monarrez cremated her daughter's remains, and last year she spread the ashes at a beach in the Pacific Coast city of Mazatlan in southern Mexico. But she kept one piece of the clavicle and sent it to a laboratory in San Francisco for a DNA analysis that cost her $1,200. She was told the remains were likely that of her daughter, but that only another costly test would give her a 99 percent certain answer. Out of money, she gave up her quest.

"I still have doubts that that is my daughter, but I don't know," she said. "Maybe I don't want to know."

Like the other mothers of the victims of the campo algodonero, Monarrez never believed Uribe was the girls' killer. She kept badgering authorities until about a year ago, when she gave up, emotionally exhausted.

"Now we're at zero again, and I don't know if they're investigating or not. But I don't believe in the law anymore," Monarrez said. " I believe in the law from up above. There, everyone pays and whoever killed my daughter, he will pay."

Benita Monarrez, with her granddaughter, says there has been no justice in the 2001 killing of her daughter, Laura.Laura Berenice Monarraz, pictured here at age 12, was found dead at age 18.Mothers from Chihuahua bear photos of daughters who remain missing. About 40 women have disappeared while hundreds have been slain.