May 14, 2015 1:45 PM EDT

When Gillian Laub started photographing the racially divided town of Mount Vernon, Ga. — with its segregated homecomings and proms — she stumbled onto the story of Justin Patterson, a 22-year-old black man who was killed, on Jan. 29, 2011, by Norman Neesmith, a 62-year-old white man.

Patterson’s story, which further divided Mount Vernon, is the subject of Southern Rites, a HBO documentary premiering on May 18.

Dedee Clarke, Justin’s mother, spoke to TIME.

Sha’von, Justin and Santa, 2012
Gillian Laub

“When I got the call, it was around 3.45 in the morning and my youngest son, Sha’von, said that Justin had been shot and he was dead… For a long time, Sha’von wouldn’t talk about it, he would only tell me things in bits and pieces. It wasn’t until 2013 that he told me the whole story. I think that the thing that bothered him the most was that the gun was actually aimed at him. Justin looked back, saw that and pushed Sha’von out of the way and took the shot himself. It’s something I don’t think he’ll really recover from. He just has to learn to live with it. It’s a day-by-day process, but I don’t think anybody can ever be the same.

The first time I met Gillian was in 2010. My youngest son, Sha’von, was attending the prom that year, and she was photographing it. I thought the work she was doing was great. But I didn’t know that much about her, I just knew that the pictures that she was taking were important. I didn’t get to know her on a deeper level until my son, Justin, died.

[When Gillian shifted her focus to what had happened to Justin], I was, at first, a little reluctant. But I could just see her passion and drive as she talked to me and I knew at that point that she really cared. I was more relaxed around her and I began to open up. But I just remember saying that it wasn’t going to be pretty sight because I was just not in the right state of mind, and she understood that.

You have to feel some kind of compassion when you do this. And Gillian had that; she felt it. And because she felt it, I believed that shows in her work.

Of course, it was very difficult to see Norman Neesmith in Gillian’s film. I had always made it a point not to really look directly at him. And to see him up close and personal in the film, it was very hard. It was hard to watch some of the things that he said. It’s just hard to hear that he never really acknowledged that his daughter invited them into his home. I felt that he thought he was a victim. I don’t think he understands that Justin had a life. He had a daughter. And she will never have her father.

Gillian’s work makes me feel that my son’s death was not in vain. That’s the one thing that I can hope for. I’m hoping that it will help someone. It’s too late for my son, but maybe it can help somebody else.

I’m hoping it will help other mothers to see that you can still survive that kind of pain and. I’m a survivor because God says I am. Everything that I believe in is because of God. He’s the reason that I’m here because there’s no way I could have done any of this by myself. I felt like nobody really cared because the story wasn’t out. It was a while before it was even in a paper. To see it now and to know that people really care, it does make me feel supported. It definitely does. I’m thinking that everyone will have an idea of what happened. This is real life. These people are real people; they feel that pain continuously every day.

My goal here is for people to know and understand that there’s still, very much so, a lot of injustice in this world and something has to be done about it.”

Southern Rites by Gillian Laub premieres on HBO on May 18. A book, published by Damiani, will be released in June.

Contact us at letters@time.com.

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