Australian singer and songwriter Sia has filed a lawsuit in an attempt to reveal the  “identity thief” seeking her unreleased recordings, reported the Rolling Stone magazine on Oct 24. Sia claims that the unidentified defendant, thought to be living in California, has been reaching out to music industry insiders over email during the past few months, demanding material that’s not publicly available. Sia is hoping the Los Angeles legal system can help her to expose the “thief”.