POLICE are pinning their hopes on the seven-year-old daughter of victims Saad and Iqbal al Hilli holding the key to tracing the killers.

Final confirmation of the victims' names came from the couple's youngest girl Zeena, four. But when police officers asked what she could recall, she told them she did not see anything because she "dived under her mother's legs".

Investigators are now hoping her older sister Zainab, who is in a medically induced coma, might provide the vital clues they are looking for as she is the only other witness.

Doctors do not know when she will be fit enough to be questioned.

Police say Zainab, who was shot in the shoulder, may only have been spared because the killers had run out of bullets.

"When doctors give us the green light, she will be questioned," said chief investigator Eric Maillaud. "It's awful for a child, a victim, to be a key witness, because she will have to talk about her own suffering, but we do hope that at seven she is old enough to tell us what she saw. She can tell us the colour of skin, the colour of clothes and other information we need."

Mr Maillaud added: "Zeena talked about fear, terror, and at the beginning of this carnage she was already under the knees of her mother and this other woman. The little girl was terrorised, she was in the vehicle, she rushed under her mother's legs and she heard but she didn't see anything. Very soon we have to make sure she comes to the safety of her family and starts to calm down and forget this nightmare."