London: The police conducted a search operation at the house of the victim, Iraqi-born businessman Saad al-Hilli, 50, who was shot dead along with his wife and two others in South London for possible clues.
As per a BBC report, the search was carried out by two French officers along with Surrey Police.
The help of Italian and Swiss authorities has also been sought.
Earlier in the day, the brother of Saad, had denied any dispute over “financial matters” in the family.
The shocking murders took place when three members of a British family and a cyclist were killed at an Alpine beauty spot.
The victim and his dentist wife Iqbal and her mother were shot in the forehead through the car windows as they sat parked in a remote forest lay by. A French cyclist thought to have been a witness was found shot dead nearby.
According to French police, the brother of the victim, Zaid, will be questioned as a witness. The police suspect that family dispute could be one of the motive of the crime and are investigating on these lines as well.
The family was on a caravan holiday near Lake Annecy, France. The couple`s seven-year-old daughter Zeinab managed to escape from the car before being shot in the shoulder. She was in a medically induced coma in a French hospital.
While Zeena, four-year-old sister of Zeinab, survived unhurt as she hid herself in the footwell of their car underneath her mother`s body for eight hours.
Officers believe the family may have been lured to the spot for a planned execution by a hitman.
Police were stunned by the ruthlessness of the attack by a clearly expert gunman who fired "clinical shots to the centre of the forehead".
According to French police sources, the clinical manner of the killings - with a total of 15 shots fired - pointed towards a planned execution.
(With Agency Inputs)