If I report a tenant in my building who deals dope from his apt., can I be protected from threatened harm?

He is a severe manic-depressive w/ clinical narcissism (diagnosed) and in a state of extreme mania told me the details of his "business". Later, in a very different state of mind, He threatened me with bodily harm if he was busted. Which means I'm in danger even he if he is busted for another reason. This was a peaceful neighborhood before he moved in a year ago and now he has so many young people getting high, in the presence of small children, and angry that they may lose their source. He is a monumental coward who has several of his "customers" keeping an eye on me. I've lived here for years and love it here and I'M NOT GOING ANYWHERE! My landowner is an attorney who trusts me to keep an eye on things, but I don,t know how much he can protect me if I tell him. My question is to any law inforcement officers, lawyers out there. This individual vaguely indicated that he obtains the dope from a gang located in a nearby city and they would harm me. This is very serious.