What if a dangerous person lives in an apartment building and threatens tenants?

My daughter lives in an apartment where a male tenant (they call the Squatter) harasses girls, follows them, corners them in the laundry, bangs on doors. Rental company does nothing, police called multiple times, say nothing can be done until someone is "hurt." He has pushed people, broken cell phones during filming. Can she get out of her lease since she is afraid for her own safety in her own building and own apartment? Rental company refuses to even admit to the problem despite calls, emails, etc.