A British engineer murdered in the French Alps a year ago recorded all of his phone calls giving police "some very precise details."
Ten months after his brother's murder in the French Alps, Zaid al-Hilli has moved from witness to suspect.
Two British girls who survived the killings of their family in the Alps are to be interviewed by police as the search for answers continues.
Sources in France suggest the man arrested in connection with French Alps shooting is the brother of Saad Al-Hilli - Zaid. He was arrested at an address in Chessington on suspicion of conspiracy to commit murder
A man held by police in connection with the deaths of the Al-Hilli family in the French Alps last year has been arrested on suspicion of conspiracy to commit murder.
Surrey Police said the suspect, who they did not name was held at an address in Chessington at around 7.30am on Sunday "and is currently in police custody where he will be interviewed".
Surrey Police set up a Joint Investigation Team to work with French police on solving the brutal murders.
The al-Hillis' four-year-old daughter Zeena lay undiscovered under her mother's corpse in their BMW for eight hours after the shooting, while her seven-year-old sister Zainab was found with serious injures after being shot and beaten.
Surrey police said today's arrest was pre-planned and the result of on-going inquiries.
A 54-year-old man was arrested in Surrey today in connection with the murders of Saad and Ikbal Al-Hilli, Mrs Al-Hilli's mother Suhaila al-Allaf, and cyclist Sylvain Mollier, who were all shot dead near Annecy, in the French Alps in September last year, Surrey Police said.
Zainab al-Hilli's health is understood to have improved in recent days, allowing her to travel back to the UK.
– A POLICE SOURCE IN ANNECY
Zainab left France this morning at around 8am. Police from Britain accompanied the little girl.
French prosecutors have told ITV News that the search for a black Mitsubishi Pajero with British number plates is "not connected at all" with the French Alps shootings.
Sky News is reporting that French police investigating the fatal shooting of a British family in the Alps are looking for a black Mitsubishi Pajero with British number plates.
Eyewitnesses told French police that the driver of the car looked "rather nervous", according to the news channel.
Surrey Police has told ITV News that Zainab al-Hilli, the seven-year-old British girl who was wounded in the French Alps shootings in which her parents were killed "is returning to the UK."
She has been in hospital being treated for a fractured skull and gunshot wounds suffered in the massacre.
Surrey Police have said that they had held an "extremely productive" meeting with senior Gendarmerie officers, the Crown Prosecution Service and a French prosecutor and judge leading the investigation into the shootings of four people in the French Alps.
– Surrey Police
The meeting has been extremely productive and progress has been made in relation to a number of issues arising from the challenges and complexities of an enquiry across two judicial processes in aninvestigation such as this.
The meeting built on the already established strong working relationships between all parties involved.
The UK and French authorities are extremely pleased with the progress which has been made.