She Cried Murder (1973)

A model, while riding in the front car of a subway train, witnesses a woman being pushed in front of the train. But when the police come to interview her, she recognizes one of them as the man who did the pushing. She spends the rest of the movie trying to convince the good cop, that Telly is a bad cop; and Telly spends the rest of the movie chasing her around the city and finally to the subway yards. Only now the police, having finally been convinced, have joined in the chase.