The new witness last night revealed that the family had arrived at an isolated mountain car park at least an hour before they were killed. He also said there was no sign of any other vehicle following the family, suggesting they had arranged to meet the killer or were victims of a random attack.
Laurent Fillion-Robin, 38, was doing building work on a house in Chevaline when he saw the family's red BMW approaching. He said he saw the car between 2.30pm and 3pm. The shooting was reported to police at 3.58pm by a former RAF serviceman who was cycling past.
"I saw an English car coming up the road from the village," said Mr Fillion-Robin, who has not yet been interviewed by police. "There were no other cars with it. I did not see or hear any other cars pass by that afternoon."
The house is the final property before the road climbs 3km to the car park in a national park above Lake Annecy.
Police have revealed that the Iraq-born Mr Hilli, 50, his dentist wife Ikbal, 47, his Swedish mother-in-law Suhaila al-Allaf, 74, and a cyclist, Sylvain Mollier, 45, were each shot two times in the head and that 25 bullets were fired in the attack.
Mr Fillion-Robin said: "I didn't hear any shooting. You do hear shooting from the hunters sometimes but I didn't hear anything that afternoon. Perhaps they had a silencer."
The builder, who lives in a nearby village, said it was "bizarre" for the family to have gone to the car park. "It is not the sort of place that families with young children or older people would go to," he said.