Dog Watch (1997)

A San Francisco detective goes wild when he discovers his partner dead and the presumed culprit standing over him. After beating the man to death, he comes to his senses and realizes that he has to get rid of the body of the beaten man. Dumping the man in the river, he returns to his partner's body and calls in the death. He is then given a new partner and is assigned to investigate the death of a man just pulled from the river causing all the expected problems. However, the investigation does lead to police corruption and his own partner's involvement in drug running.