My coop abuses people with mental disabilities

I am upset and need some support because my neighbor who I am friendly with, told me how the coop abuses him. They make threatening phone calls where they threaten to burn his apartment down and hurt him. They threaten his sister who lives a distance away that they will harm both off them. She has cancer. They bang on his ceiling all night so he can’t sleep. All of this is the more disturbing because they threatened me and my family with similar things. They get rogue cops and emergency service people involved in harassing and putting people in mental hospitals and even killing some people and our so called liberal district attorneys cover up even premeditated acts of violence. I live in NYC. The cops have been more respectful lately but hearing his story brought back trauma for me and made me angry that this is being allowed to happen. Any help would be appreciated.