The senior French police officer investigating the death of a British man and his family in the Alps is flying to the UK on Thursday.
Prosecutor Eric Maillaud told a news conference that cooperation between the two countries was important because “a great number of clues will be in the UK”.
“There are three big areas of inquiry which we are focusing on: the victim’s job, family and Iraq,” said Maillaud.
Saad al Hilli, his wife, mother-in-law and a passing cyclist were shot dead while on holiday last Wednesday. His two daughters survived. Police are still waiting to interview the eldest – Zainab – who was shot in the shoulder and battered over the head.
Maillaud said prosecutors are still waiting to interview her.
“We’ll be listening carefully to every word she says, that’s very important. But for now we have to wait for her health to improve and for her doctors to confirm that she’s well enough.”
Al-Hilli’s four-year-old daughter Zeena returned to Britain and is under the care of social services.
The victims’ bodies have now been returned to their families.
Relatives said they were heartbroken by the tragedy and called for whoever carried out the killings to be brought to justice.