LONDON (AP) -- J.K. Rowling says her crime-writing alter ego Robert Galbraith had respectable sales and two TV adaptation offers before he was exposed as a pseudonym for the "Harry Potter" novelist, and she wishes she could have kept her identity secret a little longer.
Rowling said Wednesday that "Robert was doing rather better than we had expected him to," selling 8,500 copies in print, audiobook and e-book formats of thriller "The Cuckoo's Calling," which was published in April.
Writing on Galbraith's author website, Rowling said "Robert was doing rather better than we had expected him to."
"At the point I was 'outed', Robert had sold 8,500 English-language copies across all formats ... and received two offers from television production companies," she wrote.
"The Cuckoo's Calling" was published to good reviews as the fiction debut of a former military man working in the civilian security industry. But a newspaper revealed earlier this month that Rowling had written the book under a pseudonym.
Since then it has topped best-seller lists, with publisher Little, Brown and Company printing hundreds of thousands of new copies.
There was speculation that Rowling or her publisher had leaked the news to boost sales, but last week a law firm that has done work for Rowling admitted that one if its partners had let the information slip to his wife's best friend, who tweeted it to a Sunday Times columnist.
"If anyone had seen the labyrinthine plans I laid to conceal my identity (or indeed my expression when I realized that the game was up), they would realize how little I wanted to be discovered," Rowling wrote.
She said she took a pen-name because "I was yearning to go back to the beginning of a writing career in this new genre, to work without hype or expectation and to receive totally unvarnished feedback."
"I hoped to keep the secret as long as possible," she said. "I'm grateful for all the feedback from publishers and readers, and for some great reviews. Being Robert Galbraith has been all about the work, which is my favorite part of being a writer."
Rowling said she had taken the name from her political hero, Robert Kennedy, and a name she'd invented in childhood, Ella Galbraith.
She said she only realized too late that some people might find a clue to her identity because of the famous economist J.K. Galbraith — "but thankfully nobody was looking that deeply at the author's name."
Rowling, who followed her seven Harry Potter books with a novel for adults, "The Casual Vacancy," last year, said she has finished a second Robert Galbraith book featuring detective hero Cormoran Strike, to be published next year.
She also confirmed that she had signed a few copies of the book under her pen name, after working on a fake autograph. Bidders have offered thousands of dollars for signed first editions of "The Cuckoo's Calling" on online auction sites.
"While we can't verify whether any particular book currently on eBay etc. is genuine, any future books I sign in this way will be authenticated," Rowling wrote.
"My Robert Galbraith signature is distinctive and consistent; I spent a whole weekend practicing it to make sure."