Perry Mason - Season 9 Episode 11
The Case of the Silent Six

Police Sgt. Dave Wolfe warns Joe Oliver to stay away from his kid sister, Susan. Now Susans been beaten up in her apartment, Oliver has been shot to death, and Dave is being charged with murder. Daves story is that someone knocked him out and used his gun on Oliver. When Perry investigates the circumstances surrounding that night he discovers that six people in the building heard Susans cries but did nothing to help her and that it was not Joe Oliver who beat her up. The wrong man was killed.