07/19/2013 AT 08:50 AM EDT
Mystery solved – and Harry Potter
creator J.K. Rowling
is none too pleased.
In yet another surprising twist to a true-life tale that's becoming as fanciful as her work, Rowling's own law firm admitted that one of its partners leaked the information as to the true authorship of The Cuckoo's Calling
, a critically acclaimed debut detective novel credited to Robert Galbraith but, in fact, written by Rowling.
In a statement released Thursday through Rowling's publicist, the author says, "A tiny number of people knew my pseudonym and it has not been pleasant to wonder for days how a woman whom I had never heard of prior to Sunday night could have found out something that many of my oldest friends did not know."
Rowling continues: "I had assumed that I could expect total confidentiality from Russells, a reputable professional firm and I feel very angry that my trust turned out to be misplaced."
As for how her identity became known, apparently attorney Chris Gossage told his wife's best friend that Galbraith was actually Rowling, reports The New York Times
That friend, Judith Callegari, then spilled the beans in a Twitter exchange last week with The Sunday Times of London
, before deleting the messages.
After the newspaper confronted Rowling, she admitted to writing the book under a pseudonym, and the newspaper published an article identifying her as the author.
As a result, a once-overlooked book suddenly became an international bestseller.
In light of the controversy, Russells, a London law firm known for its work in the entertainment industry, released its own statement.
It read, "Whilst accepting his own culpability, the disclosure was made in confidence to someone he trusted implicitly. On becoming aware of the circumstances, we immediately notified J.K. Rowling's agent.
"We can confirm that this leak was not part of any marketing plan and that neither J.K. Rowling, her agent nor publishers were in any way involved."