A British family gunned down in the French Alps may have been the victims of a random killing, the prosecutor investigating the case has suggested.
Eric Maillaud said he has still found no motive for the murders of Iraqi-born engineer Saad al-Hilli together with his wife, mother-in-law and a French cyclist near lake Annecy in September.
But although investigators are keeping all lines of inquiry open, they have moved away from initial suspicions that the answer lies in a family dispute between Mr al-Hilli and his brother Zaid.
Mr Maillaud, Annecy's chief prosecutor who is leading the case, told the BBC: "Without doubt we are looking for someone who has killed before, someone who puts no value on human life.
"We are not sure whether that means it's a professional hit but if it was done on a contract it was very badly done.
"We are looking for unbalanced people - capable of extreme violence," he added.
"People who have access to weapons - hunters, collectors, shooting club members, some of whom could have had psychiatric problems.
"We are searching a huge area stretching into Switzerland and Italy - and that includes a large number of people."
Mr al-Hilli's family have expressed their anger at being investigated for the killings, with his brother strongly denying a spat over their father's inheritance had anything to with the deaths.
But Mr Maillaud said it was the "first obligation of any inquiry to eliminate the immediate family".
Engineer Mr al-Hilli, 50, of Claygate, Surrey, and his dentist wife Iqbal, 47, were brutally murdered along with her mother Suhaila Al-Allaf, 74, and cyclist Sylvain Mollier, 45, in the horrifying gun attack in woodland near the village of Chevaline on September 5.
The al-Hilli's four-year-old daughter Zeena lay undiscovered under her mother's corpse for eight hours after the shooting, while her seven-year-old sister Zainab was found with serious injures after being shot and beaten.
According to the 7-year-old survivor, both she and her father were outside the car when the shooting started, however her father tried to flee under fire before the car became trapped on the verge.
About 100 police officers in Britain and France are investigating the murders in an investigation which spans France, Switzerland, Italy, the UK, Sweden and southern Spain, where Mr al-Hilli's father had an apartment.
In the interview, Mr Maillaud all but rejected recent speculation that Mr Mollier, who worked in the nuclear industry, was the killer's main target.
"We are 99% sure he was nothing to do with it," he said.