Police are investigating whether a family feud could be behind the murder of three members of a British-Iraqi family and a passing cyclist in the French Alps.
A child survivor was unable to provide detectives with new clues.
Local prosecutor Eric Maillaud said yesterday that British police had told French authorities of a financial dispute between the British man killed in the shooting and his brother, but he cautioned against drawing early conclusions.
"It seems that there was a dispute between the two brothers about money. This seems to be credible information coming from the British police," Maillaud said.
"The brother will have to be questioned at length. Every lead will be meticulously followed."
He added it was difficult to imagine how a family feud could "pass from a financial dispute to a quadruple murder".
A French police source said the brother of victim Saad al-Hilli, a 50-year-old Briton born in Iraq, had presented himself to British police earlier in the day to proclaim his innocence and co-operate in the investigation.
Maillaud also said police had questioned the 4-year-old girl who spent eight hours after the shooting hiding in a car beneath her dead mother's skirts but that she was unable to provide significant information.
"She was questioned again last night, but without giving many more details. We have to be extremely careful about the declarations of a traumatised little girl," he said.
Maillaud said autopsy results on the victims' bodies were due overnight and the response to a formal request for DNA samples from Britain was expected to arrive over the weekend.
Hilli, his wife and mother-in-law were killed in the shooting on Thursday in a French Alpine tourist area, along with the local cyclist.
Each was shot in the head in a killing that bore many of the hallmarks of a professional assassination and that prosecutors described as an act of "extreme savagery".
Two young daughters of the victims survived, including the 4-year-old and her 7-year-old sister, who was seriously injured after being shot in the shoulder during the attack and suffering a fractured skull from what authorities said were "extremely violent" blows to the head.
Maillaud said the older girl had undergone surgery.
"She was operated on again, she is doing well," he said. "Her state of health is no longer causing much worry. She is out of danger."
He said the formal request for DNA samples and a search of the family's home was sent to Britain yesterday morning.
Police were hoping to "find certain things in the home that could give us leads on the killers".
Neighbours in England said Hilli was an engineer. They identified the other victims as his wife Iqbal, who was carrying an Iraqi passport, and his mother-in-law, who had a Swedish passport. The couple's daughters were named as Zainab, aged 7, and Zeena, aged 4.
The victims' bodies and the surviving girls were discovered in a forest car park near the village of Chevaline in France's picturesque Haute-Savoie region, which is popular with tourists including many Britons.
Three of the bodies - a man in the driver's seat and two women in the back - were found inside a British-registered BMW estate car.
The body of the fourth victim, a man, was lying nearby.
Authorities in France identified the fourth victim, a cyclist who apparently stumbled across the scene by chance, as Sylvain Mollier, a father-of-three who lived in the area and worked in the nuclear industry.
The family had been staying near where they were killed since September 3 at the Saint Jorioz camp site, where fellow campers reported their disappearance on Wednesday.
A Royal Air Force veteran who has a second home in the area discovered the victims, having cycled into the carpark at 3.48pm on Wednesday.
Several witnesses reported seeing a car speeding away from the scene. Investigators believe an automatic pistol was used and 15 spent bullet casings were found in the area.
The killer did not appear to have fired indiscriminately.
The French President, Francois Hollande, has vowed "everything will be done to find the killer or killers".