By JUAN FORERO

RIOSUCIO, Colombia - At 15, Leida Salazar had just learned to ride a bike, eagerly watched after her smaller siblings and was among the extroverts in a throng of giddy indigenous girls. But a year ago, she fashioned a noose out of a wraparound skirt, hoisted it over the wood-beam rafter of her home and hanged herself.

A note she left for her father voiced anguished fears that Colombia's drug-fueled guerrilla war would engulf her family, refugees to this poverty-stricken village along with dozens of others. But the death of the outwardly happy girl continues to confound her parents and the leaders of a once-sheltered indigenous tribe, the Embera, who never before knew suicide.

"When it happened, I thought it was the conflict," said Marino Salazar, 33, Leida's father, sitting on a stool next to the room where his daughter died. "But there are other children who can continue to stand it."

The Embera and three related tribes, the Wounaan, the Katio and the Chami, who hunt and fish in this northern swath of thick rain forests and limitless waterways, have helplessly watched as 15 young people, many of them girls barely out of puberty, have committed suicide since March 2003.

With barely 3,000 people in the tribes the yearlong spate of deaths adds up to a suicide rate of 500 per 100,000 people. The overall suicide rate in Colombia was 4.4 per 100,000 in 2003, according to government statistics.

"For us, for one to die is like losing 100," said Victor Carpio, a Wounaan leader.

Colombia's 40-year conflict, pitting rebels against right-wing death squads and state security forces, is an easy culprit. But it is not the only one. Encroaching modernity, from logging to settlements, threaten the Emberas, who worry that their whipsawed young are losing the indigenous identity at the root of the tribe's existence.

More troubling still is how to deal with a plague - psychiatrists call it a suicide epidemic - in a clan of hunter-gatherers who have little understanding of the complexities of mental disorders and their ramifications, including suicide.

"It is a mystery and of terrible concern to us," said Jorge Alzate, who works with the United Nations High Commissioner for Refugees in the region. "The problem is trying to determine exactly why."

The U.N. refugee agency, which has long aided the displaced here, has embarked on an assistance program to help stem the deaths. Financing is funneled to the Embera's shamans, known as jaibanas (pronounced hie-bah-NAHS), so they can reach nearly inaccessible hamlets by motorboat to conduct rituals. Teachers have been trained to nurture students and to spot trouble signs in young people scarred by war.

Embera leaders have gone further, asking for help from mental health professionals.

But sending a team of outsiders into this dangerous region is harder than it sounds. Colombia has no psychologists trained to deal with indigenous groups like the Embera, with many members who barely speak Spanish and have no experience with Western forms of therapy.

Tiziana Clerico, a United Nations communications officer who is a psychologist by training, also said it was unclear if the inhabitants of remote villages would accept treatment. "Here, the idea may sound fine," said Ms. Clerico, minutes after holding a meeting with several Embera women in Riosucio, a mostly Afro-Colombian village here in the Choco Province. "But it could be different out in the reservations."

What everyone does agree on is that the stakes could not be higher. Embera leaders say that as many as 25 other young people have tried to commit suicide, generating intense fears in isolated communities that bad spirits, in essence the unburied souls of the war dead, are possessing the young.

Suicide is rare in Latin American Indian tribes that are intact and thriving. But in the United States, Canada and in a few tribes in Latin America, suicide rates have risen among tribes caught in the vise-grip of the modern world, fighting for survival.

In Brazil, the Kaiowa, with some 30,000 people, have seen hundreds of young people take their lives in the last two decades as the tribe has fought to keep loggers and farmers off its land.

In Colombia, the Guambianos in the southwest suffered a spate of suicides in the 1970's, with several young people drinking poison. And in 1997, the Uwa, near the Venezuelan border, drew worldwide attention when they threatened mass suicide in a successful protest to stop oil production.

"These are groups that are facing a very bleak future," said Jeanne Jackson, a medical anthropologist at the Massachusetts Institute of Technology who has been studying Colombia's Indians since 1968. "And the response is not just migrating to urban areas and disappearing, but it's something much more pathological."

Suicide is, of course, related to mental disorders like depression and substance abuse, said Dr. David Brent, an adolescent psychiatrist at the University of Pittsburgh School of Medicine. But cultural disintegration and transition can erode traditional supports and values that affect parents' skills in raising children, self-esteem and hope for the future, which in turn can precipitate these type of problems, Dr. Brent said.

Although the literature on suicide in Latin American tribes is scant, Dr. David Shaffer, a professor of psychiatry at Colombia and an expert on adolescent suicide, said there were parallels between the Embera deaths and the cases of multiple suicides he has studied in the United States.

Once the first suicide or two takes place, receiving widespread attention, what was once seen as unacceptable behavior can become an option for other teenagers who are troubled for one reason or another, or who are depressed, Dr. Shaffer said.

The Embera, whose existence once revolved around the hunt for monkeys, deer and other game that filled the rain forest, have seen their lives inexorably altered.

In a five-day tour, Indians here in Riosucio - a honky-tonk town increasingly home to displaced Emberas - and in two secluded Embera hamlets spoke about the pressures on their communities and the deaths that resulted.

Some say that the idea of suicide might have begun after four young Indians from an adjacent tribe, the Arquia, committed suicide between 1998 and 2000. Then, on a December day in 2001, Nelson Guaseruca, who was in his 20's and lived in the Embera's most important hamlet, Union Embera, walked into the woods with his hunting rifle and shot himself. The death, apparently spurred by the death of his wife, introduced the tribe to suicide, village elders said.

On March 15, 2003, a 12-year-old Embera girl hanged herself.

The deaths continued throughout 2003 and 2004. The last suicide occurred in April, but indigenous leaders say that others have since attempted to kill themselves, only to be saved by relatives.

Carmen Casama, 19, recounted how she had felt that "something had taken a hold of me," prompting her to try hanging herself from a tree. Her husband found her unconscious and untied her. Another girl, Yarledys Tocamo, 14, was found tying a noose.

"She had some sort of attack," her mother, Luz Angela Velasquez, said. "She screamed. She acted like someone was going to take her. Others were not so fortunate."

Marvilia Marmolejo lost two of her children to suicide, Ketty Salazar, 15, and Yuber Salazar, 18. "I did not think this could ever happen," she said, as a group of other concerned parents listened. "This had never happened around here before."

In an insular jungle community like Union Embera - the village has 380 people and has had 5 suicides - the deaths are often attributed to supernatural forces.

"She was fine, but then she fell in love with a witch," José Dojirama, 45, said of his sister, Rosa Elena Jumi, 17, who hanged herself in April in Union Embera. "She treated him badly, so he said to her, O.K., but you'll get it in the end."

But indigenous leaders, with one foot in modern Colombia, acknowledge that conflict, poverty and desperation play a role.

"The jaibanas say its the spirits, but looking at it all, it could be the violence, too," said Arinson Salazar, 38, governor of Union Embera.

What is clear is that the Embera have been squeezed in the last 20 years, their world grown tighter. Settlers have depleted the jungles of animals, like the tapir, that the Embera once hunted, forcing the once-nomadic tribe to form permanent communities. They turned to farming, which they have yet to master.

Guerrillas and paramilitaries have brought more disorder, recruiting young members of the tribe. The vast river ways that the Embera and other tribes fish have become transit zones for cocaine and arms smuggling. Hundreds of Indians have been displaced by war, and 30 Embera have been killed since 1996.

The army, to shut off supplies to guerrillas, limits the amount of food that can be moved into regions where the Embera live, leading to shortages.

Displaced or pushed by economic need, young people have left their villages to face a world in which they cannot compete, said Ciro Pineda, an anthropologist who has lived in Choco for 20 years. Many young Embera do not speak Spanish well, and cannot read or write. Entering the larger world, they become quickly and painfully aware of their inabilities.

"They feel so lost that some say, 'I'll kill myself,' '' said Mr. Pineda. "They feel small. They lose self-esteem."

The question now facing the tribe is how to prevent more deaths. Many of the Emberas are certain that another round of suicides is coming. After all, the shaman, the jaibanas, have been predicting it.

Delia Casama, 53, an Embera who with United Nations financing is meeting with youths to talk about their lives, said the focus must be on emphasizing the good. "We want to take away that idea they have, that I don't want to live," she said.

In Riosucio, in his simple wood-frame home, Marino Salazar is still stumped. His daughter Leida seemed happy, he recalled, holding a picture of a smiling girl in a green dress and pink shirt.

Still, he added, he has moved on, for the sake of his other four children. He watches over them closely.

"What else can I do?" he said. "I just try to talk to my other kids."