The Harry Potter series made J. K. Rowling one of the most famous authors on the planet, and as such she's stayed a bit under the radar since wrapping up the series in the summer of 2007. She's only published one non-Harry Potter book since, last year's The Casual Vacancy — or at least that's how it seemed. However, according to The Sunday Times, Rowling is the scribe behind a mystery novel called The Cuckoo's Calling, a book that was released in April to positive reviews but minimal sales. The book, which Rowling released under the pen name of Robert Galbraith, apparently only sold 1,500 copies in hardback since its release — but now it's already the top-selling book on Amazon in the US and the UK.

The Sunday Times acted on an anonymous tip to investigate the circumstances behind the book and eventually was able to get Rowling to confess. "I had hoped to keep this secret a little longer, because being Robert Galbraith has been such a liberating experience," Rowling said in a statement. "It has been wonderful to publish without hype or expectation, and pure pleasure to get feedback under a different name." Rowling's publicist also confirmed that Rowling was behind The Cuckoo's Calling. "We can confirm it, but we are not making any further statement," Nicky Stonehill told The New York Times.

As to how The Sunday Times found Rowling's secret identity, it started with an anonymous tweet to the paper's arts editor Richard Brooks which claimed that the book was not written by a first-time author but by one of the world's most famous novelists. After a quick exchange, the Twitter account was deleted, but Brooks then did more research (including having a linguist analize both The Cuckoo's Calling and Harry Potter and the Deathly Hallows) and eventually just emailed a blunt inquiry regarding the true authorship of the novel. By yesterday morning, Rowling had decided to just fess up. While it's entirely possible the whole situation was part of a campaign to drum up attention for the book, it's also just as possible that Rowling wanted to get her book out there without the inevitable hype.

Update: The book is now the top seller on Amazon Kindle less than a day after the revelation.