A Florida-based Cuban family has prompted the U.S. State Department to investigate Madrid’s Prado to determine if the museum violated a law that makes it illegal to traffic in works of art owned by a U.S. citizen that were nationalized by the Cuban government.

The case involves the exhibition of two paintings by Spanish artist Joaquín Sorolla — Summer (1904) and Clotilde Strolling in the Gardens of La Granja (1907) — that were on display at the museum from May 26 to Sept. 13. In August, the Fanjul family asked the museum to immediately withdraw the Sorolla paintings from the exhibition and return them to the family or to the Art Loss Register, where they have been listed as stolen property since 1993. The Fanjuls’ art collection was seized under the Castro regime and their home turned into an art museum after the family fled Cuba in 1959.

Last month the Prado said it was looking into the matter and seeking legal counsel in Spain and in the U.S. According to the 1986 Helms-Burton Act, if the State Department finds the Prado guilty, the museum director, his spouse, and his children could be denied entry into the U.S.

Read more at the Art Newspaper.