Police are investigating the first murder on an island for more than 40 years after a teenage boy was found dead.
The body of Liam Aitchison, 16, was discovered in a derelict building in the Steinish area of Stornoway on the Isle of Lewis last Tuesday.
Northern Constabulary said they were treating the death as murder following a post-mortem test.
The teenager had been missing for a week when his body was discovered.
Police from the mainland have travelled to Lewis to help with the investigation.
Officers want to trace any witnesses who saw three people in hooded tops in Steinish village at around midnight on Tuesday.
Detective Chief Inspector Kenny Anderson said: "The response from the community in Stornoway to appeals for information has been very positive and I would appeal to anyone who may have information in relation to this crime to contact the incident room at Stornoway police station.
"In particular, we wish to trace witnesses who may have seen three people wearing hooded-type tops, who were seen walking in the Steinish village area shortly after midnight on Tuesday 22 into the early hours of Wednesday 23 November."
Mr Aitchison was from Uist but had been living in Stornoway for the past couple of months. He was last seen on Tuesday November 22 at around 9pm in the Anderson Road area. He may have been in the Co-op in Macaulay Road that same evening.
In a statement released last week, Liam's family said his death was "heartbreaking".
The last murder on Lewis was in 1968 when 80-year-old Mary Mackenzie was found dead in her cottage on the west side of the island in Brue. A man was reportedly charged with her murder but the case was not proven.
In 2006 a murder inquiry was launched into the death of Murdo Macdonald but the murder charge was reduced to serious assault when it reached court.