Chilling new theory in mystery murder of Brit family in Alps suggests four victims were killed in ‘psychotic attack’

A CHILLING new theory in the mystery murder of a Brit family in the French Alps suggests the four victims were killed in a "psychotic attack".

Brit businessman Saad al-Hilli, 50, wife Iqbal, 47, and his mother-in-law Suhaila al-Allaf, 74, were executed at point-blank range in their BMW car in September 2012.

Their two daughters - Zainab, who was seven at the time, and Zeena, who was four - survived.

French cyclist Sylvain Mollier, a 45-year-old father-of-three, was also found dead alongside the family car.

The mass murder has baffled French and UK detectives for close to a decade.

Now, a report by a UK psychologist asked to help in the investigation revealed the killings may have been completely random.

The unnamed clinical professional concluded the killer was a local and highly likely to have been a man aged between 30 and 40.

The expert claimed the heinous attack was an isolated incident by a loner who may have been suffering with psychosis.

"I envisage the theory that the perpetrator of the Chevaline attacks acted due to their own motives, entirely independent of the victims in this case," the report, published in the French newspaper Le Parisien, reads.

Earlier this month Zainab - now 16 - gave dramatic new details that may help to finally solve the cold case.

French investigators told Le Parisien that Zainab has offered "a testimony of unique precision about the drama".

She said she and her loved ones were enjoying a drive through mountainous countryside by the village of Chevaline on their holidays when they pulled over.

Zainab got out of the car with her father.

She recalled seeing cyclist Mollier, and while other members of the family were getting out of the car "gunshots rang out".

Zainab was ordered back into the car by her parents, but then the shooter grabbed the girl from behind.

"She first of all thought it was her father, but then saw the white skin and bare hands of her attacker, and realised it couldn’t be him," it was said.

"Zainab struggled but couldn’t get out of the grip. According to her, the killer was wearing long trousers and a leather jacket."

Zainab was then pistol whipped and blacked out after suffering multiple facial injuries.

She later made a full recovery and returned to the UK, where she now lives.

Sources close to the case have also sensationally told Le Parisien that Brett Martin, an Englishman who came across the dead bodies while out cycling, is still considered a suspect.

Martin, a former RAF officer who is now aged 63, was the first to discover Zainab staggering around an isolated country layby.

In January, a local businessman was re-arrested and released.

Original probes focused on a financial dispute in the UK between Saad, from Claygate, Surrey, and his accountant brother Zaid, who was arrested for conspiracy to murder in 2013 before being freed without charge.

Zaid has always protested his innocence.

A year later, police looked into dark theories that Iraqi-born Saad was killed over links to ousted tyrant Saddam Hussein and arrested a suspected Iraqi contract killer, who was also released.

That line of inquiry has now been dropped, it's believed.