but despite his surroundings, inmate shawn shields was in high spirits. when he sat down with us, he was eager to help our producer get the interview under way. >> quiet on the set you boneheads. >> it's a prison, you know. >> let's roll tape. >> then he calmly told us how he got 16 years added to his original sentence of 12 for robbery. >> me and another inmate had an altercation, i manipulated the door so that it wouldn't latch completely. and when he came out to walk, i came down after him and proceeded to stab him. >> why? was it because you guys weren't getting along. >> it was just a verbal altercation. >> does that happen a lot in here? >> there is a lot of verbal altercations between people. you've got to understand, there's 16 men living together behind closed doors with stress, animosity towards one another in some cases. it's not always a pleasant place to be. >> when inmates erupt, no one is safe. including correctional staff. >> we had an inmate that was on his way to the rec yard and came behind an officer and used a derogatory statement tow