Police take hunt to Italy and Switzerland in attempt to find al-Hillis' killers

The investigation into the massacre in the French Alps was extended yesterday to Switzerland and Italy. The Annecy public prosecutor, Eric Maillaud, said that it was possible that the killer, or killers, had fled to Switzerland, only one hour away, or to Italy, 90 minutes away.

In other developments, British and French police began their search of the Surrey home of Saad al-Hilli, who was shot dead on Wednesday along with his wife, an older woman and a French cyclist. The French authorities also revealed at a news conference that all four victims were shot twice in the head at close range. Previously, investigators had spoken of one shot to the head. But Mr Maillaud said that autopsies completed on Friday night showed that each of the victims had been shot at least three times, including two shots "directly into the head".

He refused to say how many guns had been used and of what type. He had hinted earlier in a TV interview that investigators now believed that there were two or more killers.

Saad al-Hilli, 50, was killed in his car alongside his dentist wife, named by neighbours as Iqbal. 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. The couple's four-year-old daughter, Zeena, lay undiscovered under her mother's skirt for eight hours after the murders, while her seven-year-old sister, Zainab, remains in a medically induced coma after being shot and beaten.

Four senior gendarmerie detectives, who arrived in Britain on Friday, held a "strategy" meeting with British police yesterday morning. The seniority of the French team suggests that investigators are convinced that the solution to the mystery of the savage killings will be found in Britain. The delegation is led by Colonel Marc de Tarlé, the most senior gendarmerie detective in France, head of the gendarmerie's "national criminal investigation bureau". Later, two of the French officers observed while police searched the al-Hilli home at Claygate, Surrey, for any document that might offer an explanation for the killings.

As the four detectives entered the house, the differences between the French and the British could not have been clearer. In contrast to the dark suits favoured by their British colleagues, an unsmiling French detective was casually dressed, his shirt tucked over khakis, complete with designer sunglasses, and a touch of Eighties designer stubble. He was accompanied by a female detective in more businesslike white blouse and trousers. Neither of the detectives said a word, and about 40 minutes later they re-emerged from the house and drove off.

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. Police plan to look at aspects of Mr al-Hilli's life to try to find a motive for the murders and also to speak to his brother, named in reports as Zaid Hilli, who lives in Chessington, near Claygate. Widespread suggestions – supported by quotes from a letter written by Mr al-Hilli in 2011 – have referred to apparent ill-feeling between the brothers over their late father's estate. Zaid has visited British police to deny this.

The Annecy prosecutor, Mr Maillaud, revealed earlier that two mobile telephones had been found on the bodies of the victims. They were being checked to discover whether they contained messages suggesting that the al-Hilli family had been lured to an ambush. The prosecutor 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. The apparent pace of progress may be judged from the prosecutor's statement that he does not expect to hold another press conference until the middle of next week.

The crime scene, at the top of a narrow, winding road above Lake Annecy, was sealed off by police once again yesterday afternoon after being opened to the press and public on Friday. Local people had begun to make the pilgrimage to the massacre site to leave flowers and messages of condolence.

Witnesses have said they saw a green four-wheel-drive vehicle in the area at the time of the killings, and possibly a motorbike. Gendarmerie investigators, including dog teams, have now begun an expanded search for clues within a 4km radius. They were searching, among other things, for signs that the killers may have fled over mountain paths or forestry tracks rather than along the steep, twisting road which is the only public access for cars to the scene of the massacre. "They are going to examine every mountain hut or shelter, everywhere possible," said gendarmerie colonel Sylvain Hamel. "We have no special reason to think we might find something. We are just being thorough."

Earlier, two unidentified relatives of the al-Hilli family, accompanied by a British social worker, arrived in Grenoble to visit the survivors of the massacre, the two sisters, Zeena and Zainab. Zainab remains in an artificial coma at Grenoble University hospital after several operations on her fractured skull. The younger girl was unhurt in the attack but spent eight hours cowering in terror at her dead mother's feet before she was found. It is understood that she will be returning to Britain with her relatives.

The al-Hillis' youngest 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 to try to confirm the woman's relationship to the family.

Making sense of the jigsaw: The conflicting theories

Professional hit

For Killing of all adults; relatively small number of bullets fired; fatal head wounds; speed of the whole incident; swift getaway; killing of cyclist bystander.

Against Bullet cases left at scene, beating of seven-year-old girl (who was shot in shoulder, not the head). Motive absent – so far.

Mistaken identity

For As above, but the al-Hilli family not the intended victims.

Against As above, but hard to imagine anyone mistaking such a group for another target.

Robbery

For Number of similar incidents in France.

Against Savagery of shootings excessive for robbers; victims not obviously wealthy, nor known to be carrying large sums of money.

Attempted abduction

For Presence of older daughter outside car, wounded but not dead.

Against Killing of all adults who might have paid any ransom.

Political killing

For Mr al-Hilli's Iraq connections, involvement in businesses which could relate to defence interests.

Against Such defence connections pure conjecture; savagery; killing of other adults and serious injuries to one daughter. Mr al-Hilli British resident for more than 30 years.