Instead, the men shot the family and fled, taking the two Mercedes belonging to the parents. But they left behind a witness, Nicolas' girlfriend Ebru, who, despite also being shot in the head, was able to raise the alarm and give police a description of one of the men.

Shortly after, a third man, identified as Frédérique M, was picked up driving one of the stolen cars in Luxembourg. He denied any involvement in the shooting and said he was paid simply to deliver the car to France. He is fighting his extradition back to Belgium.

The two shooters are described as Christian L, a 28-year-old Belgian, and Milton R, a 30-year-old Congolese man. Magistrates said traces of both the men's presence had been found in the De Vleeschouwer home. Neither has a criminal record in Belgium.

At the time of going to press, it was reported the two were refusing to cooperate with French police or to give any sort of statement. The Brussels prosecutor has begun proceedings to have them extradited to Belgium.

Police said the two were caught following a telephone investigation carried out after the arrest of Frédérique M in Luxembourg. They were traced to the family apartment of Milton R in Sainte-Geneviève-des-Bois, a Paris suburb. Both were arrested on the street by French police, in the presence of a squad from the federal judicial police based in Asse, Flemish Brabant, who travelled to France to help coordinate the arrest.