Four people gunned down in the French Alps had each been shot twice in the head, prosecutors have revealed.
Saad al-Hilli, 50, was killed in his car alongside his dentist wife, named by neighbours as Iqbal, on Wednesday.
An older Swedish woman travelling in the car also died in the shooting, along with Sylvain Mollier, 45, a French cyclist who apparently stumbled across the attack in Chevaline.
A police officer accepts flowers outside the home of French shooting victim, Saad al-Hilli
The couple's four-year-old daughter Zeena lay undiscovered under her mother's corpse for eight hours after the murders, while her seven-year-old sister Zainab remains in a medically induced coma after being shot and beaten.
Post-mortem examinations revealed each of the victims killed in the attack had been shot a number of times, including two hits to the head, public prosecutor Eric Maillaud said.
Police are searching the al-Hillis' family home today in Claygate, in Surrey, after a team of four French officers arrived in the UK.
The caravan which the family had been staying in at the Le Solitaire du Lac campsite in Saint-Jorioz was also removed by police.
French authorities have now asked their Italian and Swiss counterparts to help them in their hunt for those responsible.
Surrey Police erected a tent at the front of the al-Hillis' home today as they prepared to conduct a search of the property with the French police team, led by officer Marc de Tarle.
Two French detectives entered the house earlier with British officers, while scenes of crimes officers in full protective suits are continuing the search this afternoon.
Families have been visiting the home throughout the day to leave floral tributes outside the front of the house. Along with bouquets of flowers, teddy bears had been left and a Mr Men 'Little Miss Trouble' book.
Two relatives of the al-Hilli family have travelled to France, alongside a British social worker, and will visit the girls who are under police supervision.
However it was unclear when they would be able to see the elder girl, Zainab, as she continues to be treated in hospital.
Mr Maillaud said the identities of the relatives who had arrived in France would not be made public for "security reasons".
Police plan to look at aspects of Mr al-Hilli's life to try to find a motive for the murders and also speak with his brother, named in reports as Zaid Hilli.
British and French police officers outside the home of French shooting victim, Saad al-Hilli in Claygate, Surrey
Investigators have disclosed that Mr al-Hilli's brother approached UK police to deny any feud with his sibling over money.
Speaking at a press conference today, Mr Mauillard said the brother would be interviewed along with the rest of the al-Hilli family as part of the investigation.
He said: "He will be interviewed just as all of the rest of the al-Hilli family, who are going to be identified in the coming days."
The al-Hillis' four-year-old daughter has spoken to police and confirmed that two of the victims were her parents, but said she did not know the Swedish woman very well.
Mr Maillaud said they were working with Swedish authorities as they try to confirm the woman's relationship to the family.
Witnesses have said they saw a green four-wheel-drive vehicle in the area at the time of the killings, and possibly a motorbike.
All the victims were shot at least three times and investigators have found 25 spent bullet cartridges at the scene on the outskirts of a forest near Lake Annecy.
Mr Maillaud said the family had visited France a number of times before and it was not the first time they had been to Le Solitaire du Lac campsite.
One theory is that shots could have been fired during a bungled armed robbery, with Mr Mollier being a witness to the crime.
But speculation about other possible motives, including a pre-planned attack by professional hitmen, remained rife.
Some media reports have suggested that Mr al-Hilli, an engineer who left Saddam Hussein's Iraq several years ago, was known to the security services and was put under surveillance by Metropolitan Police Special Branch during the second Gulf war.
A Scotland Yard spokesman said they could not comment. But it is understood there is no link between the deaths and any national security issues.
In a joint statement by British and French officers outside Woking police station, Assistant Chief Constable Rob Price said Surrey police have sent family liaison officers to France.
The head of operations for Surrey police said: "This is a French-led investigation.
"Surrey police will do all we can in the support of the effective investigation on behalf of our French colleagues.
"Throughout that support I want to place the emphasis on the victims of this tragic incident and Surrey police, again working with our French colleagues, will be ensuring all those who need support will get the support.
"Specifically, Surrey police have deployed specially trained family liaison officers both here in the UK and abroad in France."
Colonel Marc de Tarle of the Gendarmerie said cooperation "both on the human level and the technical level" between the British and French authorities was going smoothly.
SEE ALSO:
- French Alps Shooting: Dead Father, Saad Al-Hilli, 'Known' To Security Services (PICTURES)
- Francois Hollande Says Police Will Do Their 'Utmost' To Find Family's Killer
- British Al-Hilli Family Named, Father Saad, Mother Iqbal Killed, Daughters Zainab And Zeena Survive
- Killed Cyclist Named As Sylvain Mollier