i'm john segenthaler. >>> due to mature subject matter, viewer discretion is advised. >>> there are 2 million people behind bars in america. we open the gates, "lockup." >> you get close to somebody, but you can't trust that person because that person might be the one to stab you. >> down here on the floor, one of the inmates was actually brutally burned. >> step back to the door. >> they can smell fear, especially in a female. >> this system needed a wake-up call. i broke my tv, made a couple shanks and assaulted them. >> i was covered from my neck down with blood. >> i have heard and i've seen what he's done to other officers. >> i would just like to get on with my life and get my freedom back. >> one of the greatest challenges facing prison officials across the country is protecting the safety of both inmates and officers in an extremely predatory environment. with many facilities overcrowded and understaffed, that task can be difficult if not possible. in the next hour on "lockup," we'll go beyond the scenic desert landscape to the penitentiary of new mexico, a prison that is batt