. >> here is colorado state penitentiary. this time, estrada is in for murder.a crime he committed after being released from his first prison term. >> in here you take things a lot more serious, somebody calls you a punk, somebody calls you a bitch, something says i'm going to kill you, in here, that means, you know, you hold them people to that word, to them words then. when i got out and them guys were saying that about me, i'm going to kill john, i'm going to do this to him, the first thing in my mind is well i better go kill him before he gets me, you know? even though he was probably talking out of his ass. he really didn't understand the type of person that i am and where i've been and the thought process that i've learned in here. and he's dead now for it. it's kind of like a kill or be killed. >> estrada's prison education started early. >> how old were you when you were first arrested? >> when i first -- about 13, 14. >> what did you do? >> stealing a stereo out of a car. that's how it all began. start out stealing bubble gum at the stores, all the way

. >>> nestled at the base of the rocky mountains, colorado state penitentiary was built to house the ate's most violent and disruptive inmates. it gives new meaning to the words hard time. >> we decided that csp could not be a place where inmates could get comfortable and make a life for themselves. we had to treat them differently. >> colorado state isn't just any maximum security prison. it's a super max facility. inmates here are considered a constant threat and are confined to single-person cells 23 hours a day. >> i was astounded by how sterile and stark and what tough time it would be to serve in that particular prison. i think that would be the hardest time possible. >> many of the inmates we spoke to agreed. they say the isolation is too much. >> i've been here a long time. i've seen a lot of guys, seen them snap, you know? any given day they can snap. >> 23 hours a day you're locked down. you come out for five hours a week. essentially it's just another cell. it's a dead room with a pull-up bar. there is window where you can get some fresh air. that's it. # everywhere you go,

. >>> the day we arrived at colorado state penitentiary, a super max prison at the base of the rocky mountains, we found a sterile, austere environment, steel doors behind which inmates are locked up 23 hours a day, 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 >> it's a prison, you know. >> all right. 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 it happen a lot in here? >> there is a lot of verbal altercations between people. you got to understand. there's 16 men living together behind closed doors with stress, animosity toward one another in some cases, and it's not always a pleasant place to be. >

. >> when we met edwin smith, he had been at colorado state penitentiary for less than a month just starting a 30-year sentence for cutting a man's throat in a bar fight. he lost his television privileges for spitting on an officer during intake and things were about to go even further downhill. >> mentally, you have to take it [ bleep ]. you can't really fight with someone. >> the night before our interview with him, smith had received a lesson in supermax security when he chose to hold up in his cell. >> we're here to perform a cell extraction on inmate smith, edwin. the reason for the extraction is the inmate refused to come out for a cell search. >> smith's actions triggered colorado's emergency response team. one of their primary functions is to extract uncooperative inmates from their cells. >> when our crews follow a cell extraction, it's one of the most intense moments on "lockup." it's when an inmate refuses to cuff up or come out of the cell or is doing damage to the cell and the special response team is called in. >> need you to cuff up. if you refuse to cuff up we will introduce

. >> bill hankins, a long-term inmate at colorado state penitentiary knows about sudden explosions. during a routine strip search, hankins snapped. >> i used to get frustrated. i would be worked up, just wanting to, you know, get at them. >> hankins is serving life without parole for killing a grocery store clerk during a robbery. in this super max facility he is not allowed contact with other inmates. but he is released from his cell for an hour of daily solitary exercise. it's what keeps him going. >> being locked down all day long, every day for 23 hours a day and coming out in a little room to work out, you know, was a difficult first couple of years, but then i realized, you know, i'm just giving myself high blood pressure. >> while "lockup" crews have shot dozens of workout routines, the strangest has to have been at the miami-dade county jail where the two inmates covered their faces to remain anonymous. >> i'm a trainer, you know? >> after a round of what they called bed lifts they showed us how they do chin ups in the showers. but correctional staff took a dim view of their