Pablo Picasso's stepdaughter said 407 works by the late Spanish artist were stolen from her chateau in southern France.
Catherine Hutin-Blay, 65, told Le Parisien newspaper she noticed the works were gone in 2011, when the Picasso Administration - manager of the Spaniard's estate - alerted her that several Picassos were on sale at a private gallery in Paris.
Hutin-Blay recognized the titles as among the works she inherited from her mother, Jacqueline, who was Picasso's second wife, and soon confirmed that the pieces were indeed missing from the chateau in Vauvenargues.
The robberies apparently took place between 2005 and 2007, Hutin-Blay told the newspaper.
Le Parisien said artworks were also taken from the home of Hutin-Blay's neighbor, Sylvie Baltazart-Eon, the 58-year-old daughter of Picasso's art dealer, Aime Maeght.
Freddy Munchenbach, who performed unspecified work for both women, is suspected of making off with more than 600 works belonging to Baltazart-Eon and Hutin-Blay, according to the newspaper.
Besides the Picassos, the haul included pieces by Kandinsky, Joan Miro, Antoni Tapies, Giacometti and Eduardo Chillida.
The works stolen are worth as much as 2 million euros ($2.6 million).
Hutin-Blay said she has recovered 22 of the looted works.