Story highlights J.K. Rowling secretly wrote "The Cuckoo's Calling"

The publisher pretended the author was Robert Galbraith, a former soldier and police officer

It's been "wonderful to publish without hype or expectation," Rowling says

Sales on Amazon spiked 507,000% after the news broke

"Harry Potter" creator J.K. Rowling donned an invisibility cloak of her own for her new novel.

In top-secret fashion, she published "The Cuckoo's Calling" under the name Robert Galbraith. Her publisher, Mulholland Books -- an imprint of Little, Brown and Company -- described the author as a former member of the Special Investigative Branch of the Royal Military Police.

"He left the military in 2003 and has been working since then in the civilian security industry," the publisher's website said. "The idea for (protagonist) Cormoran Strike grew directly out of his own experiences and those of his military friends who returned to the civilian world. 'Robert Galbraith' is a pseudonym."

The Sunday Times, curious about who this mystery novelist really was, connected the dots -- noting that "he" used an agent, editor and publisher who had worked with Rowling.

"I 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 from publishers and readers under a different name.

JUST WATCHED J.K. Rowling praises joys of pseudonym Replay More Videos ... MUST WATCH J.K. Rowling praises joys of pseudonym 02:42

JUST WATCHED Rowling's secret is out, sales are up Replay More Videos ... MUST WATCH Rowling's secret is out, sales are up 01:51

JUST WATCHED Why do authors use pseudonyms? Replay More Videos ... MUST WATCH Why do authors use pseudonyms? 04:35

"The upside of being rumbled is that I can publicly thank my editor David Shelley, who has been a true partner in crime, all those people at Little, Brown who have been working so hard on 'The Cuckoo's Calling' without realizing that I wrote it, and the writers and reviewers, both in the newspapers and online, who have been so generous to the novel.

"And to those who have asked for a sequel, Robert fully intends to keep writing the series, although he will probably continue to turn down personal appearances."

While the novel received praise before the secret was out, the disclosure that Rowling was the author -- to little surprise -- skyrocketed the book's sales.

Reagan Arthur, publisher of Little, Brown and Company. said a reprint of the book is underway and will carry a revised author biography that reads 'Robert Galbraith is a pseudonym for J. K. Rowling.' "

On Amazon.com, sales soared more than 507,000% after Rowling acknowledged being the author.