The fourth book, "The White Death", will be released in Swedish in August.
During the year, the fifth part will also be published in Swedish, according to Mius publishing house.
So far, there have been seven books about the private detective Cormoran Strike. Rowling has previously said that she plans to write ten, all under the pseudonym Robert Galbraith.
J.K Rowling began using the pseudonym in 2013 when she started writing for adults after the success of the books about "Harry Potter". After the real author behind the crime novels was revealed, sales are said to have increased by thousands of percent.
The series about Cormoran Strike has sold more than 20 million copies in 40 different languages.
