A man has been jailed for six years for throwing a brick through a lorry driver's windscreen, causing him to suffer a fatal heart attack.
Michael Little was praised by police for keeping his lorry under control
Michael Little, 53, was driving along the M3 last year when the brick was hurled at his 40-tonne lorry.
Craig Harman, 20, of Glamis Close, Frimley, Surrey, admitted manslaughter at the Old Bailey.
Mr Little, from Hornchurch, Essex, managed to steer his vehicle to safety off the motorway but died later.
Death 'within moments'
The case is thought to be the first time a successful prosecution has been brought in England where a killer has been traced through a relative's DNA profile.
Surrey Police took DNA samples from the brick which hit Mr Little on 21 March 2003.
Harman had left his DNA on the brick but could not be identified as he had no criminal record.
But forensic experts traced a close relative who was on police records and detectives were able to use the family link to trace Harman, who was arrested on 30 October.
The technique, called familial searching, had been launched only months earlier.
The brick went through the windscreen and hit Mr Little's chest
Harman, a shop assistant, had denied Mr Little's murder at an earlier hearing, but pleaded guilty to manslaughter.
The Old Bailey was told Mr Little was between junctions three and four of the M3 near Camberley, Surrey, when the brick was thrown from a footbridge at about 0030 GMT.
Mr Little, who drove for Ford for 26 years, was commended for his actions in steering the lorry to safety, managing to save other drivers from harm.
Mark Dennis, prosecuting, said: "Death would have occurred within moments, which makes Mr Little continuing to control his lorry and bring it to a halt even more commendable."
The court heard Harman had drunk at least eight pints of lager during the evening and was walking home with a friend.
They tried unsuccessfully to steal a car before Harman threw the brick from the bridge, the court heard.
Craig Harman said he threw the brick to "annoy drivers"
Harman's not guilty plea to the murder charge was accepted by the court after he admitted throwing the brick to "annoy drivers and interfere with traffic flow".
His sentence will be served in youth detention until he is 21.
Mr Little's partner and sister both said outside court they were disappointed with the leniency of the sentence.
His sister Beverley Little said: "I suppose in a way we were hoping that, because of the seriousness of the attack, that some sort of example would be made.
"But it doesn't appear it has been."