Saad al-Hilli, 50, of Claygate, Surrey, wife Iqbal, 47, and her mother Suhaila, 74 were shot point blank in their car near Lake Annecy in September 2012. The eldest daughter Zainab survived after being shot once in the shoulder and pistol-whipped.
Youngest daughter Zeena, who was then only four, survived as she was hidden under her mum’s skirt in the backseat of the car.
However ex-DCI Mark Preston, who was Surrey Police’s investigating officer on the case, believes that the Anglo-Iraqi family were not the intended target.
He argues that murdered cyclist Sylvain Mollier, 45 who was from the nearby town of Ugine was the intended target of the killer.
Mr Mollier was found dead on the ground having been shot first and last with more bullets than were used to kill the entire family, according to ballistics evidence.
Mr Preston argues that the family were murdered as they were witnesses to the killing of Mr Mollier.
However, when soon after the attack French prosecutor Eric Maillaud visited Surrey he argued that the answers to the case lay in Britain.
Suspicion fell on Saad’s elder brother Zaid as the two men had feuded over inheritance.
The case is due to feature in a forthcoming three part Channel 4 documentary and Mr Preston feels that certain lines of inquiry were closed too soon.
READ MORE: Pensions set to rise by 10 percent with triple lock reinstated
“With no motive against Saad or Iqbal being the target, and the evidence at the scene not suggesting the al-Hillis were the target, we’re then left with two theories: one is a lone gunman, or that Mollier was the target.
“From my perspective, there wasn’t as much scrutiny of Mollier being the intended victim as there had been of the al-Hillis being the intended victims.
“I do think that the depth to which we delved into the al-Hillis got to the point where we could absolutely prove that they were not the targets.
“With Mollier, there were still questions.”
Mr Preston has effectively ruled out the idea of a lone gunman due to the lack of sightings and the fact that Mr Mollier was shot first and last.