Dean Geary appeal: 'His family really want closure'
7 February 2014 Last updated at 12:56 GMT
The family and friends of teenager Dean Geary who was found by a passer-by on the A811 are renewing an appeal for information about what happened to him.
The teenager, from Alexandria, had been on a night out with friends in Glasgow earlier in the evening.
CCTV footage shows Mr Geary at Queen Street station with his friend Mark Craig and later in the city's George Square.
On the fourth anniversary of Mr Geary's death Mr Craig says: "For his family's sake, his family really want closure and all his friends as well …. somebody somewhere has got to know the reason he was there."
A police investigation concluded that Mr Geary died of severe head injuries after being accidentally hit by a vehicle.
But detectives say there are unanswered questions and are re-examining how the teenager came to be fatally injured.