Police detectives in the remote Outer Hebrides of Scotland announced Monday they were conducting their first murder investigation since 1968.The death of Liam Aitchinson, 16, which had been considered suspicious, was reclassified as a murder after an autopsy, the Stornoway Gazette reported. Aitchinson was reported missing Nov. 23 and found dead a week later in an empty Royal Air Force building near the Stornaway Airport on Lewis and Harris, the largest and northernmost of the islands.A Stornoway taxi driver told police he drove Aitchinson to a place outside the town on the evening of Nov. 22, The Guardian reported. The teen was last seen that night in the village of Steinish.The Outer Hebrides, also known as the Western Isles, has one of the lowest crime rates in Britain. The police district has the largest area in the country although the permanent population is only 26,500.In 1968, Mary Mackenzie, 80, was beaten to death and robbed on a small farm on Lewis. A neighbor was charged and received a verdict of \"not proven,\" a term unique to Scotland.In the years since 1968, police have investigated about 2,100 serious crimes with a clearance rate of 86 percent, the highest in Britain.Aitchinson had a history of minor brushes with the law and was to be sentenced Nov. 23 for an assault on an ambulance driver.