British police have travelled to France for the first anniversary of the murder of an engineer who was shot dead with his wife and mother-in-law.
Saad and Ikbal al-Hilli, along with Mrs al-Hilli's mother Suhaila al-Allaf, and local man Sylvain Mollier, were killed in the brutal attack on 5 September last year.
The attack came as the al-Hilli family, who lived in Claygate, Surrey, holidayed at a campsite near Annecy, in south east France.
Mr al-Hilli's brother Zaid, who is from Chessington, Surrey, is due to answer police bail next month after he was arrested on suspicion of conspiracy to murder amid claims he doctored documents to ensure he inherited the family estate.
On Thursday Surrey Police said officers had travelled to France for the anniversary, and French investigators are expected to give an update on the probe tomorrow.
Since the inquiry started British police have taken 60 statements, seized 5,500 documents and 1,600 exhibits, Surrey Police said, and travelled to France several times.
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 inquiry 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 inquiry in the UK."
So far the investigation has focused on three main areas - Mr al-Hilli's work, links to his native Iraq and his family.
The horrific murder scene was discovered by cyclist Brett Martin who found Mr Al-Hilli, 50, his 47-year-old dentist wife and her elderly mother blasted to death in their BMW.
The al-Hillis' seven-year-old daughter Zainab was ''stumbling'' around, bleeding and ''moaning'' near the car after being shot in the shoulder and beaten; and her four-year-old sister Zeena lay hidden under her mother's corpse and was only discovered eight hours after the murders.
The two children returned to the UK soon after the killings.