Three 16th century oil paintings that have been hanging in William Randolph Hearst's famous castle at San Simeon belonged to a Jewish couple who were forced to give them up during the Nazi reign in Germany, authorities said Tuesday.

Two of the three paintings, visible to guests and millions of tourists at Hearst Castle since 1935, will be returned Friday to the heirs of the rightful owners, both of whom died during the war, one in the death camp at Auschwitz.

The shocking discovery, made after a lawyer for the heirs filed a claim with the California State Parks, is yet another reminder of the scope of Jewish persecution during World War II.

"Never in a million years did I think anything like this would cross my desk," said Brad Torgan, the former general counsel for the state parks who led the investigation. "It is one of the most interesting things I've ever worked on and, given the outcome, one of the most rewarding things I've worked on at state parks."

Two paintings - "Portrait of Alvise Vendramin," attributed to Jacopo Tintoretto, and a painting known as "Portrait of a Bearded Gentleman," credited to Giovanni Cariani - will be returned Friday to Peter Bloch of Boynton Beach, Fla., and Inge Blackshear of Buenos Aires.

The handover will be part of an 11 a.m. ceremony at Leland Stanford Mansion State Historic Park in Sacramento, honoring Bloch and Blackshear's grandparents, Jakob and Rosa Oppenheimer, who owned a Berlin art gallery where the paintings were displayed in the 1930s.

The other painting - "Venus and Cupid," by Paris Bordone, will remain at Hearst Castle and, along with photographic reproductions of the other pieces, be used in an exhibit in which docents will explain how the Nazis confiscated Jewish possessions.

"It brings to your mind a sad time in world history," said Hoyt Fields, museum director at Hearst Castle. "We can't let it go away. We need to remember."

The three paintings are all oil on canvas done in the mid- to late 1500s. They were attributed to the Venetian masters, but Hoyt said they were actually painted by understudies or students.

In 1935, the paintings were at the Galerie van Diemen Co., which was owned by the Oppenheimers, who fled to France during Nazi rule. The Nazis, at that time, seized their assets, including all of the paintings in the art gallery.

Jacob died a poor man in Nice, France, on June 3, 1941, and Rosa was arrested by German occupiers and sent to Auschwitz. She died there on Nov. 3, 1943.

Her grandchildren apparently learned about the paintings inside Hearst Castle from a 1977 handbook showing the artwork at the Hearst San Simeon State Historical Monument.

Torgan said he spent a year and a half investigating the claim, including an extensive review of German court documents from the 1950s. It turns out that agents of Hearst bought the paintings in 1935 during an auction from another Jewish-owned gallery.

Hearst, who evidently did not know about the tainted history of the paintings, placed the Tintoretto and Cariani in the Doge Suite in September 1935. The Bardone was placed in the North Wing in September 1940. They have been there ever since.

"There would have been no red flags," Torgan said. "We would call Hearst an innocent purchaser."