As a fantasy author, (as we all know), J.K. Rowling had larger than life success with the Harry Potter series. When she decided to fulfill her dream of writing a "whodunit" (as she called it), she decided to use a male pseudonym, thus the author, Robert Galbraith was created. The name was born from her hero, Robert F. Kennedy, and a childhood favorite name of Ella Galbraith. She does not know why that name was so fascinating, but it always was. So, Robert Galbraith it was.
Galbraith wanted to go back to the beginning of a writing career, and wanted to receive honest, non-hyped feedback on her new genre. Now, she still writes as Robert to keep the distinction from her other writing.
Her ideas of writing a detective novel correlated with her work on Harry Potter and The Casual Vacancy. There should be clear rules, the detective should always explain the required information for the reader, but always be ahead of the game. Her detective had a military background which gave Galbraith many excuses to add intrigue to the novel, for example, no appearances in public or no photographs.
Galbraith says that she starts with a tiny idea of her character's personality, but ends up knowing much more about the character than ever ends up in the novel. She actually uses color-coded spreadsheets to keep track of where she is going at any given time. It was the same for the Harry Potter series. Her level of detailed planning is well documented for the Harry Potter novels. Galbraith is very disciplined with her schedule of writing, with a set working day.
One interesting, final point........she does not write the title page until the book is finished.