Is my landlord responsible for one tenant harassing another?

Question Details:

I live in a apartment complex and have lived there for 2 years. In this time I have seen 1neighbor constantly harassing another neighbor. Recently the neighbor has been harassing me and my son. We have complained to the landlord and made police reports but both refuse to do anything. We can be sitting on our porch and not say anything to her and she will start accusing us of things we did not do and calling us derogatory names. What is the landlord's or local police's responsibility in this matter? Important Notice