Russian billionaire Dmitry Rybolovlev's family trust has reportedly joined a Picasso heir as a plaintiff in legal proceedings against French art dealer Olivier Thomas. Paris police questioned Thomas last week in regards to allegations that works by Pablo Picasso were stolen from Catherine Hutin-Blay, the daughter of Jacqueline Picasso, the artist’s second wife.

Catherine Hutin-Blay says she noticed in recent press reports that two portraits of her mother now reside in the Rybolovlev collection. She had given them to Thomas for storage, claims Hutin-Blay. Rybolovlev says he did not know the artworks were allegedly stolen. He has a separate case pending against art dealer and freeport owner Yves Bouvier, an associate of Thomas.

Thomas, who is also the chairman of the Luxembourg Freeport, runs Art Transit in Paris. The Art Transit holding company is chaired by Yves Bouvier’s father.

An investigation is underway by OCBC, which oversees trafficking of cultural goods. Further questioning of Thomas may resume next week.