Hector Feliciano, the author of a book that focused international attention on artworks looted by the Nazis, has sued the estate of the Parisian art dealer Paul Rosenberg, saying he was deprived of a finder's fee for helping the family recover paintings by Matisse, Monet, Léger and Bonnard.
In his complaint, filed on May 23 in State Supreme Court in Manhattan, Mr. Feliciano said he was entitled to $6.8 million, or a 17.5 percent share of the estimated $39 million worth of paintings that have been returned to the Rosenberg heirs in recent years. He said that Elaine Rosenberg, the widow of Paul Rosenberg's son Alexandre, repeatedly made oral promises to compensate him for his efforts in tracking down the paintings, although no terms were discussed.
''He trusted Mrs. Rosenberg,'' said John Charles Thomas, a lawyer for Mr. Feliciano. ''He realizes he was naïve. It never occurred to him that someone who had reaped such a huge windfall would break a promise to him.''
A spokesman for Mrs. Rosenberg and other family members in the New York region, said that Mr. Feliciano, who now also lives in New York, had not been responsible for recovering the paintings and had no oral contract.
Founded in 1878, Paul Rosenberg & Company was long one of the most important galleries for the major masters of the School of Paris. When Mr. Rosenberg fled occupied France in 1940, he left behind an extensive collection of paintings in a bank vault in Libourne. He died in 1958 without getting all of the paintings back. The efforts of Alexandre Rosenberg, also a prominent figure in the art world, were also largely unsuccessful. He died in 1987.
According to the complaint, the Rosenbergs had given up searching for the missing art work when Elaine Rosenberg was interviewed by Mr. Feliciano in 1994 for his book ''The Lost Museum: The Nazi Conspiracy to Steal the World's Greatest Works of Art.'' The book caused a sensation when it was published in France the next year.
At Mrs. Rosenberg's request, Mr. Feliciano contends, he spent thousands of hours researching the paintings and compiling a list of the works that were still missing from Paul Rosenberg's collection. As a result of his efforts, he maintains, the family was eventually able to retrieve ''Odalisque,'' a painting by Matisse, which was found at the Seattle Art Museum in 1997; a Monet ''Water Lilies,'' found at the Boston Museum of Fine Art in 1998; ''Woman in Red and Green'' by Léger, found at the Pompidou Center in Paris, also 1998; and ''Interior,'' a Bonnard, which was withdrawn from a 1999 Sotheby's auction at the last minute.
Despite Mr. Feliciano's contention, however, others in the art world say that the art recovery process often involves a complex web of discoveries and interactions. ''Odalisque,'' for example, was spotted in Mr. Feliciano's book by a granddaughter of the couple who had donated it to the Seattle Museum; she then told the Rosenbergs of its whereabouts. It was returned to the family after a legal battle.
Sarah Jackson, the director of historic claims for the Art Loss Register in London, said it was she who discovered that the Monet was registered in a museum in the French city of Caen as a stolen work that had not been claimed. The painting was later located by Jonathan Petropoulos, the author of ''Art as Politics in the Third Reich,'' she said. She said her organization told Sotheby's and the Rosenbergs that the Bonnard was about to go on sale.
''The whole history of art looting is extremely complicated,'' Ms. Jackson said. ''It needs a lot of effort by different people to find these works of art.'' She said that 15 artworks stolen by the Nazis had been identified by the Art Loss Register, a private company. It does not charge for the recovery of art looted in World War II, said Anna J. Kisluk, the director of art services at the company's New York offices.
Mr. Thomas, Mr. Feliciano's lawyer, acknowledged that others had been involved in recovering the paintings, but he said that his client had done crucial work in compiling the inventory and tracing the works as they passed through various hands.