Styx (2007)

Investigator Mukaev is found badly beaten in a park, with complete amnesia. Returning to work, he discovers he was investigating a serial killer right before the attack. He had recently taken over the case, isolating himself with all the information. As he resumes the hunt, Mukaev learns the victims were all women he had been involved with. It becomes clear someone is framing him with evidence of guilt. Tension rises within the investigation team. The suspects narrow down, and Mukaev realizes he's the prime suspect, wishing he could stay away from his past.