THE prosecutor trying to unravel the mystery behind the killings of a British-Iraqi couple and two others says there are still no suspects but there are three leads of interest, including the possibility of a family dispute.

Prosecutor Eric Maillaud said at a news conference that a seven-year-old girl who survived the attack last week in a remote area of southeast France is a "key witness" but likely will not be the pivot to unravelling the grisly case.

She's still recovering from wounds and hasn't been questioned.

The leads are a family financial dispute, possible links to the dead driver's profession as an engineer, and the couple's roots in Iraq.

Meanwhile,relatives of the British family hope those responsible are brought quickly to justice.

In their first public statement, released through Britain's foreign ministry, Ahmed Al-Saffar said the "family and I are heartbroken by this shocking crime".

Mr Al-Saffar was identified by the ministry as brother to an elderly woman killed in the attack.

She has not been formally named, but the Sipa news agency has reported she is the Swedish-Iraqi mother-in-law of the car's driver, Saad al-Hilli.

Mr Al-Hilli, his wife Iqbal and the elderly woman were shot dead last Wednesday inside a car, while a French cyclist riding nearby was also killed.

"We hope that those responsible for the deaths of our loved ones are brought swiftly to justice," said Mr Al-Saffar.

Originally published as 'Three leads in grisly Alps murder'