Deadly Hero (1975)

After a demotion from detective to patrol duty, 18-year NYPD veteran Officer Lacy is already under scrutiny for his violent tendencies and trigger-happy behavior. When he rescues Sally, a cellist, from a deranged crook named Rabbit by shooting the attacker in cold blood, the incident turns him into a public hero, even as the troubling truth behind his methods remains impossible to ignore.