Police probing a quadruple murder in the French Alps admit they still don’t know the identity of the killer.
Three members of the British-based al-Hilli family and French cyclist Sylvain Mollier were shot in Chevaline near Annecy a year ago.
Two girls miraculously survived the shooting.
Detectives say they are still working on the theory that the murders were linked to a dispute over family inheritance.
Zaid, the brother of murdered Saad al-Hilli, was arrested earlier this year on suspicion he killed over their father’s inheritance.
He denies involvement and police have not charged him.
Annecy prosecutor Eric Maillaud, speaking at a press conference to mark a year since the murders, said they are also investigating a link with industrial espionage.
He said: “We also know that the British company that employed him (Saad al-Hilli) was working for many foreign states.
“There is still complex work to do because foreign states and industrial espionage might also mean the intervention of the secret services.
“We do not know, it is an extremely complex part of the inquiry that will require an enormous amount of time.
“It might not produce a result but the inquiry is far from over on this issue.”
Maillaud, responding to suggestions the investigation was struggling, said it was a “lengthy, difficult and complex” case and it was not “stalled”.