Russian media say the attack appears to have been the work of a professional killer, who opened fire as Usoyan left the restaurant early on Wednesday afternoon.

BBC: Russia's 'top gangster' Grandpa Khasan shot dead

Alain Fracheboud, a gun shop owner in Geneva, told me that if it is proved to be the weapon used it is "a bizarre choice for a professional killer".

BBC: News, Annecy