What Is Legal And Best For My Safety

I'm not sure if this is the best place to post but here goes. I live in the city of Atlanta, but I am in DeKalb County. I have lived in my apartment complex for over six years and my recent upstairs neighbor has been having mental breakdowns. The walls in our units are very thin with very little insulation. I can hear every conversation that my neighbor has. I heard a fight that he had with his girlfriend recently that was visiting, where he told her that he would shoot her with his gun. She called the police and as soon as they came, he would not let them in and they just left. The other night he was ranting and raving to himself like he usually does and screaming and yelling viciously at the top of his lungs that he was going to kill whoever it was that he was talking to, using all kinds of abusing language, although no one was there. He then proceeded to open the back door to the porch, which leads out to a huge grassy common area that we all as neighbors in all of the buildings share, and he told everyone that he was going to Kill them, etc., with his pistol. I alerted the Courtesy Officer who told me to call 911. I called 911 and the police came but he wouldn't answer his door so they told me that they couldn't do anything. I spoke to the manager at the leasing office and he claimed he would do something but has done nothing yet. I am very concerned that someone that is so unhinged has a gun, especially because a bullet could go Through the wall or ceiling or floor. What are my rights if I don't feel safe living in my unit anymore? Do I have a right to request to be moved on their dime (the complex) to another unit?