The Oscar given Orson Welles for “Citizen Kane” some 70 years ago goes on sale in an online auction this month, a Los Angeles auction house announced Monday.

The best screenplay award for 1941 was the only Oscar for the legendary writer, director, actor, although he was given an honorary award “for superlative artistry and versatility in the creation of motion pictures” nearly 30 years later.

Welles was 25 when he wrote, directed and starred in “Citizen Kane,” which the American Film Institute picked in 2007 as the top film of the previous century.

The golden statuette’s controversial history includes a court fight with the Academy of Motion Picture Arts and Sciences, which tried to stop another auction in 2003. An academy official testified then that the award’s value was at least $1 million.

A judge cleared the way for auction with a ruling in 2004 that Welles never signed the academy’s agreement not to sell the trophy, according to Nate D. Sanders Auctions spokesman Sam Heller.

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The academy, which aggressively challenges efforts to sell Oscar trophies, was successful three years ago in stopping the sale of two Oscars awarded to silent film star Mary Pickford. A Los Angeles jury ruled the descendants of a woman who was married to Pickford’s third husband could only sell the statuettes back to the academy for a price of $10.

Heller would not identify the seller, although it was known to be in the hands of Beatrice Welles, the actor’s youngest daughter, after she recovered it from a planned auction in 1993. It had been “assumed to be lost” for decades but was apparently in the hands of a cinematographer who got it from Welles, Heller said.

An attempt to sell it at auction in 2007 failed to draw a buyer, Heller said. It was included in a lot of historical manuscripts, not movie memorabilia, he said.

“Citizen Kane,” Welles’ first feature film, was nominated for nine Oscars but won just for best screenplay, which Welles shared with co-writer Herman J. Mankiewicz.

Welles, who portrayed a fictional media tycoon, lost to Gary Cooper in “Sergeant York” for the best actor award. John Ford’s direction of “How Green Was My Valley” beat Welles for best director.

The bidding in the online auction will end on the evening of December 20, Heller said.