Murderer (simplified Chinese: 杀人犯; traditional Chinese: 殺人犯) is a 2009 Hong Kong thriller film directed by Roy Chow, and starring Aaron Kwok. The film centers on a police detective investigating a series of gruesome murderers. As the case pulls him deeper, he soon realizes that he may be a prime suspect. The film co-stars Janine Chang, Cheung Siu-fai, Josie Ho and Chin Kar-lok, who also served as an action choreographer. Murderer is a co-production between Focus Features and EDKO Film, and was released theatrically in Hong Kong on 9 July 2009.