Dolores Lasley, one of the tribal elders, mentioned racism and poverty. But her 14-year-old granddaughter, Aleisha Pemberton, interjected: "The schools should have more metal detectors, because of the school shootings."

"Metal detectors?" the writer reflected. "Here, in this quiet place, of lakes, woods, Indian sovereignty? Even here, the larger world intrudes."

In the two days since 16-year-old Jeff Weise took his grandfather's gun, shot him and his woman friend, and drove his grandfather's police car to Red Lake high school, where he killed seven people before turning the gun on himself, it has become clear how far that intrusion has gone.

As you approach the reservation, a large sign says: "Homeland of the Red Lake Band of Chippewa, where sovereignty, traditions and heritage are preserved."

On the other side of the road another says: "Red Lake Nation is a sovereign nation."

According to the US department of justice, Indian tribes are "domestic dependent nations": Congress has power over Indian affairs but the tribes have sovereign powers over their members and their territory.

The Chippewa have used those powers since Monday to keep a strict control on the media, threatening journalists with trespass charges if they leave the one road that runs through town, and briefly detaining two photographers they believe had disobeyed.

"Repeated attempts to interview witnesses is viewed as interfering with a federal investigation," said a leaflet handed to the media on Tuesday. "Under the authority of the Red Lake tribal chairman, you may be removed from the reservation."

But drug abuse, crime, gang violence and poor education have long pervaded this wooded landscape, where 8,000 to 9,000 people live.

Four in 10 of them have incomes below the poverty line, a higher proportion than on any other reservation. In May 2001 the Minnesota national guard used the reservation to train for a mission of nation-building in the developing world.

The town's petrol station orders drivers to pay first and pump later, because there are so many "drive-aways".

Its school has one of the worst results in the state.

In January last year the FBI and the bureau of alcohol, tobacco, firearms and explosives began intensive operations in the area after locals sprayed police buildings with gunfire. Between December 2001 and July 2002 gangs with names such as Native mob and Red Nation clique were responsible for five murders.

"Red Lake is not unique," Steven Hirsh of the Centre for Reducing Rural Violence in Bemidji, 30 miles away, told the Grand Forks Herald.

"It has the same problems other rural areas are having, though they may be more pronounced because it's in a reservation setting."

But at times the reservation itself has proved to be a source of violence, tribal conflicts provoking gunfights, arson and hostage-taking.

"There has been really very substantial animosities on that reservation for a long time between various families and groups," said Paul Magnusson, a US district judge who once ordered the release of two residents who had been denied lawyers and bail before a tribal judge jailed them.

But few believe that any amount of foresight could have predicted Weise's behaviour on Monday, any more than any amount of local knowledge can explain or excuse it.

An FBI study of 18 school shootings, released in 2000, provided a profile of a likely assailant.

Those involved shared 28 personal characteristics, six family traits, seven school attributes and five social leanings, including tendencies to boast and threaten, depression, intolerance, lack of self-esteem and empathy, lack of intimacy at home and excessive use of video games and violent films.

Weise, whose father committed suicide eight years ago after a day-long standoff with the police, and whose mother has lived in a nursing home in Minneapolis since a car accident damaged her brain, displayed most of them.

His postings on neo-Nazi websites swing between intense self-loathing and ethnic supremacy, railing against racial mixing and a decline in Native American self-pride, and calling for greater segregation.

"It's hard being a Native American National Socialist," he wrote. "People are so misinformed, ignorant and closed-minded it makes your life a living hell."

The way he dressed and the way he entertained himself put off many of his schoolmates. "He wore black a lot and painted his face," said Ashley Morrison, a fellow pupil. "He was always in art class drawing pictures of skeletons, skulls; and playing guitar."

With echoes of Columbine, where the two assailants belonged to a gang they called the Trenchcoat Mafia, Ashley says he had always worn a trenchcoat. "He made drawings of people dying, Nazi symbols," said Ashley's 15-year-old brother Christofer, who said he used to hang around with Weise until some of his odd ways started to frighten him.

As is increasingly the case, the investigators have begun their work with his hard drive.

Weise's internet activity, particularly with neo-Nazi and zombie-related websites, show him posting messages as late as 4.39 in the morning. His posting name on nazi.org was Todesengal (angel of death); his instant message screen name was verlassen (desolate or lonely). His email address was decemberforthesoul@ hotmail.com.

"I suspect we'll learn that just like every other school shooting there was advance warning, a lot of information, and it wasn't acted upon," Daniel Rohrbaugh, whose son, Daniel, was killed in Columbine, told AP. "If that's not the case, this will be unique in school shootings."

But Weise's killing spree may hold lessons beyond the issues of school, disaffected youth and Indian reservations.

In the past 10 days there has been a number of gun-related attacks: a churchgoer in Milwaukee killed seven of his fellow worshippers; a rape suspect killed three people in an Atlanta courtroom; and a four- year-old shot his two-year-old brother in the head with a gun because he had stolen his toy.

But in Red Lake the issue of gun control has yet to be raised.

Yesterday students stayed away from school as officials assessed what counselling would be most appropriate for this tight-knit community, where many saw the shootings and all will have known someone who died.