The Union des commissionaires de l'Hôtel des Ventes Drouot, representing 110 commissioners at the Hôtel Drouot auction house in Paris, was placed under judicial investigation on 21 July for conspiracy, receiving stolen goods and organised theft, a judicial source told the AFP news agency Friday.
Last December, around two dozen of the so-called "Red Collars" were arrested on suspicion of a string of thefts over the years. Police recovered diamonds, a painting by Gustave Courbet, a Marc Chagall lithograph and a Pablo Picasso sketch.
The commissioners have their nickname because of their uniforms. They are also known as the "Savoyards" after the Alpine region where the all-male organisation of stock managers and delievery crews are recruited.
They oversee their own recruitment whereby each new member reportedly has to pay for a 50,000-euro bond which he can sell on to a successor when he retires. They have no internal hierarchy and select daily tasks by casting lots.
Drouot is the most prestigious of the Parisian auction houses, selling millions of euros worth of art and antiques every year, and the commissioners had operated a closed shop in the store rooms since the 19th century.
In 1860, when Napoleon III added the former County of Savoy to his French Empire, he gave Savoyard migrants living in Paris a monopoly on art-handling.
Meanwhile, a Degas and two Toulouse-Lautrec paintings were stolen from a home in the upmarket Neuilly area in the suburbs of Paris, according to reports. Thieves broke in as the 80 year-old resident was away on holiday.