The killing of Liam Aitchison has cast a spotlight on a generation of vulnerable youngsters and led the Western Isles community to question if its traditional values can survive in the modern age

Down a track, at the end of the village of Steinish on the Isle of Lewis, police incident tape dances crazily, incongruously, in the wind. The Lewis wind is always bone-chilling in its ferocity. Today it whips up off the white, tossing waves across the mudflats of the bay, rustling the cellophane of bouquets left in tribute to a murdered 16-year-old boy, Liam Aitchison. There are pink roses and a bright spray of orange and yellow flowers. "Rest in peace, Liam," a young female friend has written. "God only takes the best."

Further up the track, hidden behind the police van and the trees, lies a derelict house, once owned by the Ministry of Defence. It makes an unprepossessing grave, but Liam's body was found here by coastguards on 29 November, around a week after he was killed. He wasn't reported missing for several days. Relatives have reported being told by the police he suffered a violent death, his head repeatedly struck with sharp-edged and blunt weapons

The events have bewildered ? and frightened ? a community that has not had a murder since 1968. "When we heard it was murder, we didn't believe it," says one young woman from the main town of Stornoway, just a few miles from Steinish. She wasn't even born when the last murder, that of an 80-year-old woman, was committed. "I feel very scared," she admits.

The story of Liam Aitchison is not just that of the murder of a vulnerable boy, who had neither a permanent home nor a job, but perhaps also the tale of the passing of a way of life. "This has stained our community," says John MacLeod, 45, who had tried to help Liam in the final weeks of his life. MacLeod, who met Liam on a ferry to the island, bought him food when he bumped into him again and was also helping him with his CV. "It's the loss of innocence. It will change the place irrevocably."

Lewis is a tight little world with a distinctive way of life. There is a battle between the lure of whisky and the island's strict Free Church of Scotland. Until recent years, rowdy Saturday nights gave way to austere Sundays, when everything shut and there was no transport to or from the island. The first Sunday ferry ran in 2009. Some even claim a connection between that and the murder. You cannot, argues MacLeod, destroy one pillar of the Lord's authority and expect the rest to remain standing.

Liam came from the smaller island of South Uist, a day's travel away by ferry and bus. He wasn't a local, and he was also a different religion. (Lewis is Presbyterian, but South Uist is 70% Roman Catholic.) "I think there is a sense of collective guilt," says MacLeod. "He wasn't a native and we let him down. There are issues about hospitality."

Liam had a troubled background. Over last summer he moved back and forth between Uist and Lewis, getting in minor scrapes in Stornoway. To the young people of the Western Isles, Stornoway has always represented the bright lights. On Saturday night the streets of its pedestrianised area are packed with teenagers, whose social life consists of walking round with their friends before buying a Chinese takeaway and getting the last buses to their more rural homes. Ask young people what there is to do here and their answer is uncannily uniform: "Get pissed." But older locals talk openly of an increased drug problem. "There is a void for young people," admits one Stornoway man.

On the day he died, Liam was due in court for a minor offence committed when drunk. He had been living fulltime on Lewis for only a matter of weeks, sleeping in different places. One hotel assistant manager says he came in looking for work in the weeks before he died, but it was too difficult to take on a 16-year-old in licensed premises.

Some are asking how such a young boy came to fall through society's safety nets. He was a normal boy, but without the normal structures in his life. That an elderly person can lie dead and undiscovered is always shocking for a community. But a 16-year-old? Liam was no angel ? but neither was he a villain. He was an experimenter, a risk taker. By all accounts he was funny, charming and talented, with a teenager's natural sense of rebellion and scorn for danger. He could have made something of himself had he been allowed to grow up. "He was a fantastic kid," says his aunt, Kate Macdonald. "He made you worry sometimes, but he made you proud too."

Rumours are rife about why Liam died. Most theories involve the usual sort of petty teenage disputes: a fight over a girl, perhaps, a wrangle over stolen aftershave. The police, who have had help drafted in from Inverness, had earlier only said that they were looking for information about three figures seen in Steinish late on the night of 22 November or early the next morning, the period when Liam is believed to have been murdered, then dumped. Whether any of these are the killers, or whether Liam was one of the three is unknown. Police have conducted extensive door-to-door inquiries, with drains being lifted in the search for the murder weapon.

The horror of the fate that befell Liam Aitchison has led many to question what he might possibly have got himself mixed up in. As one 23-year-old in Stornoway commented: "There is nothing that could have warranted what happened to him." There is an awareness of tragedy on Lewis: a personal one for a grieving family and a tragedy for a community that has begun its soul-searching.

? Police announced on Saturday night that a 21-year-old man has been charged in connection with the murder; and a second man, aged 20, has been arrested.