Malice by Keigo Higashino

When writer Kunihiko Hidaka is found murdered in his home, detective Kyoichiro Kaga immediately suspects Hidaka's friend, Osamu Nonoguchi is the killer--but can he prove it? Malice details the cat-and-mouse game between the two, as Kaga delves into the friendship between Hidaka and Nonoguchi and his attempts to get Nonoguchi to confess. The mystery is an interesting puzzle that keeps you guessing until the end. It will be published in October.