He put inmates in a room with nothing but a camera and asked them to talk about their crimes.

They'll never see the outside of their prison again, but that doesn't mean they can't make an impact.

Something amazing happens when you leave a camera in a room with inmates who are in prison because they used guns. It's hard to watch, but it's an attempt to reach kids before they end up in the same kind of place.

"I took up a gun, I held it. And then this gun became my security. … I entered a movie theater with a group of friends. Then, another group of teens came in, yelling. Pretty soon, an argument erupted between my group and that group. One of them pulled out a gun and fired it. I returned fire. … I didn't think I was gonna hit anybody, but I did it anyway. A little boy was shot. He died that night." — Sing Sing inmate, "Voices from Within" video project

To jump straight to the project, skip forward to the 4-minute mark.

"I made a choice. A gun."