>> armstrong told us he chose to plead guilty even though he wasn't the hit man. >> i knew what happened. i was definitely complicit. i could have stopped it and i didn't. i can't blame anybody but myself personally. my personally. my mom and dad are married. i am from the inner city but it was in the good part of the inner city. went to one of the best schools in the bay area, saint francis high school. mostly middle class families. i don't have no excuse for being here. >> once in prison, armstrong earned an additional six-year sentence. >> the sergeant sprayed a guy in a wheelchair for no reason. i didn't like it and i harmed him. >> what does that mean? >> physically hurt him. >> and what happened? >> other police came and they physically hurt me back. >> that impulse to defend disabled inmates is now a key part of how he spends his long days in prison. >> i'm an a.d.a. supporter. that means i help the wheelchair people, anybody that have canes, wheelchairs, whatever and i'm also a slash porter. i keep the pod clean.