French police detained a 48-year-old man on Tuesday — the first French arrest linked to the grisly shooting deaths of a British-Iraqi man and three others in the French Alps nearly 18 months ago.

France Alpine Killings

This image released Nov. 4, 2013, by the SIRPA Gendarmerie is a sketch of a motorcyclist wanted in connection with the murders of four people in the Alps last year. French authorities have detained a 48-year-old Frenchman in connection with the deaths. (Associated Press)

Annecy prosecutor Eric Maillaud said the arrest of the man, a resident of eastern France who was not otherwise identified, resulted in part from dozens of witness accounts that came in after authorities in November issued a sketch of a possible suspect wearing a helmet.

"Since the police sketch was released, we've received about 40 witness accounts that have been useful … and are being verified," Maillaud said by phone. "This arrest is the first and others will surely follow."

Saad al-Hilli, his wife, an elderly relative and a French cyclist were killed in or near the family's BMW in a wooded area near bucolic Annecy Lake in September 2012. The couple's two young daughters survived, including one who spent about eight hours huddled beneath her mother's lifeless body in the vehicle.

British police in the county of Surrey — where the al-Hilli family lived — confirmed Tuesday's arrest and said it resulted from the French investigation into the case.

In June, British police arrested al-Hilli's brother, Zaid, and later freed him on bail after questioning.

Maillaud had previously cited evidence that the siblings were fighting over their father's inheritance — although it was not immediately clear whether the French arrest on Tuesday had anything to do with that theory.