One year ago today, a Claygate man and two members of his family were murdered in the French Alps.

Saad Al-Hilli, 50, of Oaken Lane, his wife Iqbal, 47 and her mother Suhalia Al-Allaf, 74, were shot dead while on a caravan holiday in Lake Annecy in September 2012.

The family were believed to have set off on their holiday from their Claygate home on August 29 and were murdered in their BMW car, which was parked in a remote spot near Chevaline on September 5.

All three victims received two bullets to the head through the window of their car.

The two Al-Hilli children, Zainab, then seven, and Zeena, then four, survived the brutal attack. Zeena escaped unharmed by cowering beneath her dead mother’s skirt and was not found by police until eight hours after the attack.

It is believed that Mr Al-Hilli and his eldest daughter were outside of the family’s car when the gunman struck, making them flee to the car, which ended up stuck on a bank whilereversing.

Zainab was shot in the shoulder and wasbelieved to have been pistol whipped in the head before being left for dead at the side of the road.

She survived after passing British cyclist, Brett Martin, put her in the recovery position and then raised the alarm for help.

Zainab was placed into a medically-induced coma on arrival to Grenoble University Hospital and remained there until she was discharged and returned to the UK with her sister.

Despite a year of investigation by French authorities, assisted by Surrey Police, nobody has been charged with the murders.

On June 24 this year, Zaid Al-Hilli, 54, the brother of Saad, was arrested on suspicion of conspiracy to commit murder.

After 36 hours of questioning by police, he was released on bail and was later rebailed until October 23 pending further enquiries.

Although many theories into the reasons for the killings have been suggested, police are still uncertain about why the family were killed.

A French cyclist, Sylvain Mollier, was also shot dead by the gunman, and one police theory, now eliminated, was that he was the intended target.

A Surrey Police spokesman said the force continued to support the French investigation into the murder of four people near Annecy, southern France on September 5 last year.

As part of the joint investigation team (JIT), established on September 21 last year, officers from the Surrey and Sussex major crime team (MCT) have been working with the French authorities to progress a number of lines of enquiry, taking 560 statements, seizing 5,500 documents and 1,600 exhibits.

This week, senior detectives are travelling to France and will be in Chevaline for the year anniversary.

Detective Superintendent Nick May said: “The tragic events of a year ago left four people dead in appalling circumstances.

“We remain committed to finding answers to what happened that day on behalf of their families, particularly for the two young girls who lost their parents. This remains a complex enquiry and we continue to have a team of officers dedicated to supporting the investigation.

“We have established a good working relationship with our French colleagues and are continuing to pursue a number of lines of enquiry in the UK.”

World's media descended on quiet suburban street

Your Local Guardian: The day after the murders in the French Alps, the names of the victims were revealed and the nation’s media descended on Claygate.

A usually quiet suburban street was overrun with reporters, television crews and helicopters circled overhead. Following the identification of Mr Al-Hilli and his family, police began searching the family home in a bid to find some clues that would help them solve the murder case.

On the third day of the search, September 10, homes in Oaken Lane were evacuated, a police cordon was put in place and a bomb disposal squad spent two hours in the road after concerns were raised about an item found.

After two hours examining the items, the Army bomb disposal experts left the scene and police confirmed the items were not hazardous.

It was later reported that a Taser stun-gun had been found at the home during a police search.

On September 13, the French prosecutor leading the investigation visited the UK to meet officers from Surrey Police.

Speaking at the time, Eric Maillaud said: “Without any doubt the reasons or the causes have their origin in this country.

“It is only by being together that we will find the murderers.”

Searches of the family home were completed in late September, but a police presence remained at the address.

The three family members were laid to rest on October 21, after a Muslim ceremony at the Imam Khoei Mosque in Queen’s Park, London.

The family were later buried in a private service at Brookwood Cemetery, Woking, next to Mr Al-Hilli’s father, who died in 2011. Mr Al-Hilli’s mother also lies nearby.

In April this year, it was revealed by a national newspaper that the murders may never be solved after an expert working for a police forensics team “accidentally contaminated” crime-scene material with his DNA.

Shortly before Zaid Al-Hilli was arrested in June, French police were investigating a number of phone calls he made to numbers in Romania.

He was questioned by police in the UK for 36 hours before being released on bail.

The investigation into the murders continues.