Lars Kepler 1 credits

Lars Kepler is the pseudonym of husband and wife team Alexander Ahndoril (born 1967) and Alexandra Coelho Ahndoril (born 1966), authors of the Joona Linna series. With nine installments to date, the series has sold 15 million copies in 40 languages. The Ahndorils were both established writers before they adopted the pen name Lars Kepler, and have each published several acclaimed novels.

Source: Wikipedia, CC BY-SA 4.0.