The home of a British man shot dead in the French Alps along with his wife and two others is to be searched by police, a French prosecutor has said.
Eric Maillaud said French and British officers were set to enter the family home of Iraqi-born businessman Saad al-Hilli, 50, in Claygate, south London.
He his wife, Iqbal, were among those killed near Lake Annecy on Wednesday.
Mr al-Hilli's brother, Zaid, has told UK police there was no dispute over "financial matters".
French police have said a family dispute about money is one of their lines of inquiry, based on "credible information" coming from the British police.
Mr Maillaud said French officers would interview Mr al-Hilli's brother in the UK as a "witness".
Three police officers from France are believed to be in the UK to investigate the shooting and a fourth officer is due to arrive later.
Surrey Police said it was helping French authorities to carry out a "complex" investigation.
"As part of this, the force is facilitating a visit by French investigators to conduct inquiries in the UK," a spokesman said.
The BBC understands the family home was originally owned by Saad al-Hilli's parents and later inherited by him after his mother left it to him in her will.
Police plan to search the house as part of efforts to gather information about Mr al-Hilli.
Mr Maillaud said: "Up until now the police in Britain were guaranteeing the safety of the house but now it's a Franco-British inquiry that is starting and we can now enter the house of Mr al-Hilli."
Mr al-Hilli's daughters survived the attack and are believed to be the only witnesses to the killings.
Both are under police protection.
Their mother, Iqbal, and a woman thought to be Mr al-Hilli's 74-year-old Swedish mother-in-law, were killed during the attack.
The fourth victim, a cyclist whose body was found near the car after apparently stumbling across the attack, has been named as 45-year-old Sylvain Mollier.
Mr Maillaud said four-year-old Zeena al-Hilli - who spent eight hours hiding in the car with the bodies before being found by officers - has told French police about the shooting that killed her mother and father during their holiday in the Alps.
The French prosecutor said that the girl had identified her family and described the "fury" and "terror" of the attack to French police.
The child said she was between her mother and the older woman in the car - who has not yet been officially named - and hid under her mother's skirts when the shootings began.
"This is a little girl who must be protected," said Mr Maillaud. "She should go back to the UK soon so that she can try and forget this nightmare."
The child's older sister Zainab, aged seven, is in a medically-induced coma in Grenoble University Hospital after being shot once and suffering head injuries.
She was found and rescued by a British cyclist - an RAF veteran - who discovered the murder scene and alerted the authorities.
During a press conference on Friday, Mr Maillaud also confirmed that each of the victims had at least one bullet in the head, and about 25 shots were fired - more than originally thought. He refused to confirm the type or number of weapons.
Investigators are looking into reports of a green or dark coloured four-wheel drive vehicle in connection with the shootings. Mr Maillaud added that such vehicles were common during the tourist season in a mountainous region.
Post-mortem examinations have been carried out on the four victims' bodies on Friday.
The al-Hilli family had arrived on holiday at the nearby Le Solitaire du Lac campsite in Saint-Jorioz on Monday and had been due to leave at the end of the week.