SYDNEY, Australia — A mystery witness who lawyers had hoped would provide evidence of an alleged pattern of inappropriate behavior by the actor Geoffrey Rush in his defamation battle against Rupert Murdoch’s Nationwide News has been formally identified as the Australian actress Yael Stone.

The Federal Court of Australia on Friday lifted an order suppressing the identity of “witness X,” as she was originally called, revealing her to be Ms. Stone, who is best known for her work in the Netflix series “Orange Is the New Black.”

In an interview published in December, Ms. Stone, 34, told The New York Times that Mr. Rush danced naked in front of her when both were starring in a 2010-11 Sydney production of “The Diary of a Madman.” She also alleged that he used a mirror to watch her while she was in the shower and sent her sexually suggestive text messages. At the time of the alleged incidents, she was 25 years old and Mr. Rush was 59.

[Read Yael Stone’s interview with The New York Times about Geoffrey Rush.]

The identification of Ms. Stone inserts a potential new element into the legal battle over Mr. Rush’s reputation, just a month after he won his defamation suit against Nationwide News, which publishes the Sydney tabloid newspaper The Daily Telegraph.