Teenager found at side of road was 'victim of a tragic car accident'

But investigations are continuing in an effort to determine how Dean Geary, 19, from Alexandria in Dunbartonshire, was in the area.

Dean's body was found by a passing motorist on the A811 near Gartocharn, by Drymen, in the early hours of 7 February.

He was lying on his back with his hands in his pockets and a post-mortem examination revealed that he had suffered "serious head injuries".

Central Scotland Police originally thought the teenager, a promising footballer, might have been the victim of a hit-and-run, or even have been assaulted. However, after extensive investigations, police say they "can now confirm" he died as a result of a tragic accident.

It is understood the driver of the vehicle that struck him came forward early in the investigation.

Medical experts and road traffic investigators from across the UK have spent weeks examining the evidence and comparing it with the driver's explanation.

As a result, police said they were now satisfied that there were no suspicious circumstances, and the driver has not been charged in relation to Mr Geary's death.

The question of how he came to be wandering about eight miles from home, possibly drunk, in the dark, on a busy single-carriageway road, with no pavement or street lighting, has now become the focus of the police investigation.

Mr Geary had been on a night out in Glasgow the evening before his death, and last night police repeated an appeal for information in tracing a taxi driver who is thought to have picked him up.

Detective Chief Inspector Willie Cravens, who is leading the inquiry, said: "The investigation has been extensive and it continues. We still need to know how Dean got from Glasgow to the Drymen area.

"Our inquiries are currently focused on taxi firms and taxi drivers in Glasgow and the surrounding area.

"We need to trace the person who gave Dean the lift.

"We are unable to confirm if Dean arrived home in Alexandria. But if he did, it would have been around 3:50am. A man fitting Dean's description was seen at various points on the A811 walking between Gartocharn and Drymen about 4:50am and 5:15am.

"We appeal for anyone who saw Dean in Alexandria or the surrounding areas to contact us."

Police are also keen to trace Mr Geary's mobile phone and wallet, which were missing when he was found. DCI Cravens added: "We have been unable to make this information public earlier due to operational reasons and we are now appealing for anyone who may have found Dean's dark brown Armani leather wallet or his Sony Ericsson mobile to contact us."

Mr Geary had been out with friends on the night before his death. They last saw him in the Tattoo nightclub in Queen Street, Glasgow, at about 1am.

Police revealed that a two- figure sum of cash was withdrawn from Mr Geary's bank account at about 3am from a cash machine near the Europa Bar, by Queen Street railway station in West George Street.

A few minutes later, Mr Geary phoned a friend to say he was in a taxi.

Police still do not know where or why he got out of the taxi.