British officials are satisfied that he was the man found in the driver's seat with his head smashed by a close-range shot from an automatic pistol.
Two women found dead in the back seat of the car are thought to have been his wife, Ikbal, and her mother. Swedish and Iraqi passports were found on the body of the older woman.
French officials said her face and that of the male victim were too badly damaged to allow formal identification until DNA tests were performed.
In Britain, attention was centred on the Surrey commuter village of Claygate, the home of the family. Throngs of photographers, journalists and police officers descended on the village in an attempt to build a picture of Al-Hilli's private life and seek clues about a possible motive.
To their great embarrassment, the French authorities struggled to explain how a 4-year-old girl, believed to be Al-Hilli's daughter Zeena, was found alive inside the car almost eight hours after the shootings - unharmed but paralysed with fear.
The little girl had taken refuge beneath the skirts of her dead mother and grandmother.
Local gendarmes did not see her and sealed the car while a top-level crime-scene investigation unit travelled by car and helicopter from Paris.
She was discovered only after other campers told investigators that the family had two children.
Soon after the shootings, another girl, aged about 8, was found by a British tourist wandering outside the car. Her skull had been fractured by "repeated blows" from a blunt instrument and she had a gunshot wound to her shoulder.
The older girl was in an artificially-induced coma at a hospital in Grenoble yesterday. Her life was said to be no longer in danger after a series of lengthy operations.
The younger girl was also in hospital under surveillance and with a senior British diplomat.
Details of Al-Hilli's life in Britain began to emerge yesterday. One line of inquiry being investigated was whether the deaths of him and his family could be linked to his role as the company secretary of the Wiltshire aerial-photography company AMS 1087, or whether his Iraqi citizenship played any role.
Surrey police said yesterday: "This is an ongoing investigation being carried out by the French police and we are unable to confirm any details about the incident."
Sources involved in the investigation told the local French media that the killings - near the village of Chevaline, 15km from Annecy - resembled an "assassination rather than a robbery which went wrong". No shots were heard, suggesting that a silencer may have been used.
The engine of the British-registered BMW was still running when a British cyclist - a retired RAF officer with a holiday home nearby - stumbled on the scene.
Having placed the injured girl in the safety position on her side - saving her life, according to French officials - the Briton found another cyclist lying dead beside the car.
He then broke the driver's side window to cut the ignition and found the three victims inside.
The murdered cyclist, later named as Sylvain Mollier, 45, a local father of three, was also shot in the head at close range. He is believed to have stumbled on the massacre.
He had earlier overtaken the British cyclist on the steep climb to the forest carpark. A four-wheel-drive car was reported by local media to have left the car park at high speed just before the ex-RAF officer arrived.
The public prosecutor for the Annecy region, Eric Maillaud, was asked at a press conference whether he believed that he was dealing with "professional killers".
He replied: "Three of the victims were deliberately shot in the head. To talk of a professional killing is conjecture but it is clear that whoever carried out this attack set out to kill."
The two children were under police protection in case the killers tried to silence "witnesses that they had believed, until now, not to exist".
Maillaud faced hostile questioning, from French and British journalists, on the failure of the 60 gendarmes on the scene to notice that the 4-year-old was alive inside the car.
He said it was crucial that the car should be "sealed off" to prevent the "pollution" of evidence which might help to catch the killers.
Heat-sensing equipment had been used to check for survivors but did not pick up the presence of the child curled up at her dead mother's feet.
"She remained prostrate beneath the skirts of her loved ones in a jumble of bags for nearly eight hours. She did not move in all that time," Maillaud said.
She was found only after campers at the Solitaire du Lac campsite beside Lake Annecy told investigators they saw two children picking apples with their mother earlier that day.
Maillaud said he believed the little girl lay petrified in the car after the gendarmes arrived because she "didn't know the good guys from the bad guys".
"She began to smile and speak in English to the woman gendarme who took her in her arms after she was rescued from the car ... She told us she heard screams and noises but she can't say much more."
Earlier, Maillaud said the little girl had "asked for her mummy and soon realised that her mummy was no longer there".
Investigators found 15 cartridge cases scattered around the car and several bullet holes in the windows but not on the bodywork.
The rounds are believed to have been fired from an automatic pistol or several automatic pistols.
Maillaud said he hoped the girls would be able to help the authorities to piece together what happened.
"At the moment, we are confronted with a crime of immense savagery," he said. "As for why these people were killed at this place and at this time, there is, so far, no way to answer that."
Independent
