JK Rowling Leveson
JK Rowling: Grown-up book Reuters

JK Rowling is turning over a new leaf: she is writing a book focusing on adult audiences nearly five years after her final Harry Potter novel.

The book will be published worldwide by Little,Brown, which already has a monster worldwide hit with the teenage vampire series Twilight.

The series was made into eight films and has even catapulted Rowling to the Forbes list of billionaires 2011 as the richest person with a literary source of revenue.

Speculation about the new book is rising with many betting on the possibility of a crime novel. The author has not revealed the title of the book or the date of publication.

She promised that her new novel would be a different experience for readers who know her as the creator of the magic world of the boy wizard, Harry Potter.

"The freedom to explore new territory is a gift that Harry's success has brought me, and with that new territory it seemed a logical progression to have a new publisher," she said.

"I am delighted to have a second publishing home in Little, Brown, and a publishing team that will be a great partner in this new phase of my writing life."