Stewart "Specky" Boyd, 40, died with his daughter Nicola, her friend and a three-year-old girl when the Audi coupe he was driving veered across a motorway on Spain's Costa del Sol and hit a BMW, killing two occupants.
Earlier investigations had suggested the former Glasgow enforcer's death could have been a professional hit over a pounds 2.5 million cocaine deal.
But Spain's chief traffic officer said there was no evidence to support claims that a timed bomb had been placed underneath the vehicle.
The cause of the accident is still being investigated by police in Spain. Scottish police have been helping with the inquiry.
Scottish Police arrested three men in connection with the assassination attempt on the brother of gangland enforcer Stewart ‘Specky’ Boyd.
Squads of officers, wearing bullet proof vests, targeted a number of houses almost five months after an armed gang tried to gun down 48-year-old Hugh Boyd in a drive-by shooting near Barrhead’s busy town centre.
The raids, all simultaneous and carried out with military precision, happened during daylight and miles apart in different housing schemes.
One source said two of the men were held at one of the house swoops. A third was detained in the wake of another raid.
The source added: “The men cops were after didn’t stand a chance – I don’t think they knew what had hit them. A squad of cops were at the door of homes one moment and inside the next.Horrified Boyd was hit as five shots rang out while he sat behind the wheel of a red Vauxhall Vectra at the junction of Southpark Avenue and Glen Street, close to Barrhead Library, at around 9.30am on August 29 last year
At the time, sources said he survived because he ducked and the bullets shot by him. He was later taken to hospital and treated for minor injuries.
Armed response officers, carrying automatics weapons, were among the first at the scene. Shocked residents said children would have been in the street if the hit had happened 45 minutes earlier. Police cordoned off the usually quiet area as forensic searched for clues.
Officers were also comparing notes on a series of other shootings in Pollok and Nitshill. And police in Paisley were checking out possible links with the Stock Street drive-by shooting last August when teenager Andrew Devlin was blasted to death. A pal with him, 26-year Gerald O’Doherty is still seriously ill in hospital.
Spanish national police probing the death of a Scottish gangster whose sports car burst into flames ruled out claims it was a Scottish Mafia assassination over a bungled drugs deal, but the full report as to the cause of the accident and the mystery surrounding the fire still remain.