Swedish author Henning Mankell, best known for the Wallander series, died Monday morning at 67 years old, after being diagnosed with cancer last year. A statement on his website confirmed the news. “He died in his sleep early this morning in Göteborg,” the site says. The Wallander series, which featured Swedish policeman Kurt Wallander, were turned into a TV show starring Sir Kenneth Branagh, who spoke of Mankell’s death.