Saad al-Hilli, his wife, mother-in-law and a passing cyclist were shot dead at Lake Annecy in France.

Police know the type of gun used in the attack, which their two daughters survived, was a Luger model P06.

France’s cold case unit has confirmed the discovery of a Luger not far from the scene of the murders in September 2012.

Marianne magazine, which broke the story, says it was British tourists who found the weapon which forensic experts are now examining.