When Miguel David Meza Argueta heard last year that his cousin Neyra, a 20-year-old computer student, had disappeared, he said he immediately flew to this city in northern Mexico to help search for her. Hundreds of young women in the border state of Chihuahua, mainly in Ciudad Juarez, have been murdered in the past decade, so Meza said he feared the worst.

He and the family searched everywhere, even driving around in the desert where scores of bodies of raped and mutilated women have been dumped. He led protest marches against the police to complain that they didn't seem to be investigating. As his family grew more angry, he called the state attorney general incompetent.

When Neyra Azucena Cervantes's remains finally turned up in the desert, Meza got his response from the police: He was arrested and charged with raping and murdering his cousin. The only evidence against him is a confession that he said was false and was signed after police tortured him.

"I asked for answers," Meza said, interviewed in a state prison where he has been held for 15 months, "and they answered me with torture and prison."

Human rights groups said Meza's case is typical of how authorities in the state have mishandled scores of investigations in Mexico's most notorious string of killings, in which more than 300 women have died since 1993, at least 90 of them in rape-murders.

Investigations by the United Nations, the Inter-American Human Rights Commission, Amnesty International, members of the U.S. Congress and other groups have repeatedly shown that local police have mishandled or fabricated evidence and failed to follow logical leads. The probes have found that police have sometimes framed suspects or tortured innocent people into making false confessions so they could claim to have solved cases.

Guadalupe Morfin, the special commissioner appointed by President Vicente Fox to coordinate the government's response to the murders, said state police were reluctant to investigate because "they are hiding acts committed by their colleagues." Rights groups and Mexican federal officials say at least some of the killings were carried out by corrupt police officers working with powerful drug cartels, which Morfin called "a collapse of the rule of law" in Chihuahua. Chihuahua police regularly torture suspects because they want to solve cases "by any means," she said.

The women's murders have become a major embarrassment for Mexico and have led to protests in the United States and Europe and even a forthcoming Hollywood movie.

"A lot of international pressure has confused the authorities," Morfin said. "They think that by offering someone up as the guilty party, it will satisfy those demands. They don't realize they are creating double victims -- the people they are falsely accusing and the families of the victims."

She said she does not believe that Meza is guilty, and she has requested a federal investigation into allegations of torture by Meza and three suspects in other women's murders. Asked if Meza, whose trial is underway, might be found not guilty, Morfin said, "We cannot lose that hope."

The man in charge of investigating the murders is Jesus Antonio Pinon Jimenez, the state attorney general. He took over in March when his predecessor, Jesus Jose Solis Silva, resigned after 17 state police officials were implicated in the drug-related murders of a dozen people who were found buried in a back yard in Ciudad Juarez.

Pinon, an 18-year veteran of the attorney general's office, was Solis's deputy. He has consistently played down the women's murders, infuriating human rights activists and victims' families. In an interview, Pinon said claims that Chihuahua has a problem with serial murders of women are "all a myth." Pinon also denied that Meza had been tortured.

Pinon said the victims' families and rights groups have exaggerated the numbers for political purposes. He said that they were "members of the Communist Party" or have "leftist ideologies" and that they want to "give a bad name to Ciudad Juarez and the state of Chihuahua."

"They are inventing that bodies are being dropped in the desert; this is not true," Pinon said. He said that only 36 women since 1993 have been killed in murders classified as possible serial sexual killings and that almost all of those cases have been solved. He said some of the dead women cited by human rights groups actually died in car accidents, from heart attacks or in falls in the bathtub.

Stanley Pimentel, a former FBI agent who reviewed more than 300 murder case files as part of a U.N. investigation, said that was incorrect. "These were young women who were kidnapped, used for a while and cast away," he said. "In every case, simple, basic investigations had not been done and logical leads were not followed. There are people out there committing these crimes, and they are still out there."

On May 13, 2003, Neyra left the clothing shop where she worked but never made it home. After family members searched for her for three days, Neyra's stepfather, Jesus Argueta, called their relatives in Chiapas, and Neyra's cousin Meza flew to Chihuahua, 1,500 miles away.

Almost immediately, Meza said, the family became frustrated with police inaction and marched in front of the office of Solis, the attorney general. They carried signs and shouted that police were either behind the killings of Neyra and the other women or were protecting the killers.

Meza and the family met three times with Solis. Meza said that the meetings turned increasingly hostile and that during the last one, he told Solis that if he wasn't willing to investigate, he should quit and let someone competent do the job.

Meza said Solis was furious and told him: "You want the responsible person? You're going to have him very soon."

A week later, on July 14, after some bones and clothes were found in the desert, Meza and Neyra's mother, Patricia Cervantes, went to police headquarters and Cervantes identified Neyra's pants, shirt and tennis shoes. Cervantes said she began crying and screaming at the dozens of police officers there. It was then, they said, that the police started treating them as criminal suspects.

Police took Jesus Argueta, Cervantes's husband, for a polygraph test. About midnight, Argueta said, they drove him to a walled and gated police complex. There, he said, they slapped him and told him that he should confess to his stepdaughter's murder. He refused.

At the same time, Meza said, police took him to a different room in the same complex. He said a police officer told him, "We know that someone in the family killed Neyra. And tonight we are going to find out who that guy is."

For the next six hours, until dawn, a dozen or more police officers tortured him, Meza said. They made him strip, then wrapped him up like a mummy in 12-inch-wide bandages, leaving just enough space for him to breathe. He said they threw water on him, then shocked him with a cattle prod. They kicked him and forced spicy water up his nose, he said, and put a plastic bag over his head until he thought he would suffocate.

"I felt like I was dying," Meza said. "So I told them I would sign anything they wanted me to sign."

Meza said the police talked it over and agreed on a story for Meza to sign. According to his confession, he was sexually obsessed with Neyra, but she rebuffed him. So he paid two men $700 each to abduct Neyra and bring her to a house on the outskirts of Chihuahua. Meza met them there, bought a gun from them for $400 and borrowed a car from them. Then, according to the confession, he drove Neyra to the desert, where he raped her and shot her in the head.

Police acknowledge that they have never found those two men or the gun and car they say Meza used. Police also have no forensic evidence that Neyra was raped; Neyra's family wondered how police could determine from a few weathered bones that this was so. Meza said his confession was dictated to him by police officers who made up the story. His mother and other family members said Meza was with them in Chiapas when Neyra disappeared.

"They know I am not guilty," said Meza, 27, a stocky man in freshly pressed jeans and a polo shirt, sitting in a small prison conference room. "It's hard on me, but it's worse for my family."

Meza's mother and sister have moved to Chihuahua from Chiapas and are living in a small house near Neyra's family. They have sold property in Chiapas to pay attorneys to defend Meza. "They've done a lot to try to divide us, but we've stayed together," said his mother, Carmen Argueta.

"They took my Neyra," Cervantes said. "I will never forgive the people who took my daughter, or the police for not investigating."

Researcher Bart Beeson contributed to this report.

Neyra was one of hundreds of women slain in the past decade in Chihuahua state. A cousin said police coerced him into taking responsibility for her death.Neyra Azucena Cervantes is mourned by her mother, Patricia Cervantes, left, her stepfather, Jesus Argueta, and their daughter Alejandra, 19. Argueta said police slapped him and told him to confess to her murder, but he refused.