- French investigators are in Britain to pursue leads in the murder case
- The brother of Saad al-Hilli may be interviewed as a witness, a prosecutor says
- Autopsy results are expected Saturday for the four victims
- Two girls whose parents were among those killed remain in France, one in a coma
London (CNN) -- French investigators probing the mysterious murders of four people in eastern France have traveled to Britain as they continue their hunt for clues Saturday to the killer's motive and identity.
They are expected to search the home of two of the victims, British nationals Saad al-Hilli and his wife Ikbal, in Claygate, Surrey, the English county where the family lived.
They are among three people whose bodies were on Wednesday found in a car, shot to death in a secluded parking lot in the foothills of the Alps, near Annecy, French prosecutor Eric Maillaud said.
The couple's two daughters, age 4 and 7, survived the attack although the elder girl suffered a bullet wound and serious head injuries.
The fourth victim was French cyclist Sylvain Mollier, found dead of a gunshot wound to the head in the same parking lot. Maillaud has opened a judicial investigation for murder and attempted murder in the case.
Three French investigators arrived in Britain Friday, with a fourth to join them Saturday.
Police in Surrey said they were helping the French authorities with their inquiries.
"This is a complex and ongoing investigation being led by the French authorities and Surrey Police is providing any assistance possible," a news release said. "As part of this, the force is facilitating a visit by French investigators to conduct inquiries in the UK."
Officers from Surrey Police have been stationed outside the Al-Hilli family's substantial home in a well-heeled neighborhood since Thursday.
Speaking to reporters Friday, Maillaud was unable to give any more idea of who might have been responsible for the brutal attack, or its motivation.
However, he sought to dampen media speculation about a possible family feud involving Saad al-Hilli's brother and a reported conflict over an inheritance.
Maillaud said he hoped the brother would be interviewed as a witness by French investigators in Britain.
The brother had gone to police voluntarily Thursday -- after learning from the media that his relatives had been shot -- to find out what happened, Maillaud said.
He went back to police of his own accord Friday to say there had been no conflict with his dead brother over money, as had been reported, Maillaud said.
The prosecutor is expected to announce the results of autopsies carried out on the four victims Saturday afternoon in Annecy, CNN affiliate BFM-TV reported.
Investigators are also awaiting ballistic reports that may reveal details of the weapon, or weapons, used to fire around 25 shots at the scene. All four of the victims were hit by at least three bullets, and all were shot in the head.
Another clue may lie in the report by a witness that he saw a green 4x4 vehicle and a motorbike near the site of the killings, outside the village of Chevaline in the mountainous Haute-Savoie area.
The couple's identities were confirmed to investigators by al-Hilli's 4-year-old daughter, who spent hours in the vehicle hiding behind her dead mother's legs, apparently immobilized by fear, Maillaud said.
The girl, identified as Zeena, has not been able to give investigators any more information about who carried out the attack, he said.
Her 7-year-old sister was found, severely injured with a fractured skull and bullet wound to her shoulder, outside the car. She is still in a medically induced coma and cannot yet be interviewed, Maillaud said. He described her survival as "a miracle."
"We hope that she will be able to tell us what she went through, provide us with descriptions of the murderer of murderers," Maillaud said of investigators' hopes for when she is brought out of the coma.
The identity of a third person who was killed in the car is not yet clear. She was an older woman with a Swedish passport, but her relationship to the others has not been confirmed, Maillaud said.
French authorities hope to return the 4-year-old girl to family members in Britain soon, once they assess to whom she can be entrusted, the prosecutor said. Although physically unharmed, she is being cared for by specialist pediatric medical personnel under the watchful eye of police and British consular officials.
Her elder sister, who has been named in media reports as Zainab, is also being protected by police in case of a further threat to her safety.
What is known about the victims is that Saad al-Hilli was an Iraqi-born engineer who lived in Claygate in Surrey, south of London, with his wife and two daughters. He was born in 1962 and was a naturalized British citizen.
He was completely unknown to French and British counterterrorism and intelligence services at the time of his death, Maillaud said.
Neighbor Jack Saltman, in Claygate, said Saad al-Hilli had come from Iraq "many years" ago and that both he and his wife spoke perfect English.
"They were a delightful family," Saltman said.
The neighbor said Ikbal al-Hilli was a dentist and the two daughters were "absolutely beautiful."
Staff at the local school attended by the 7-year-old girl declined to give a comment on the case.
CNN's Dan Rivers contributed to this report.
