. >> aaron yost was 11 years into the latest sentence when we met him in kern valley state prison in california. he says his problems stem from a near lifelong abuse of drugs. >> i grew up with drugs. my parents were quote, unquote, hippies. both my parents dropped acid. my mom's dead now from a dug overdose. when i was 9 years old, i was rolling joints for mom and dad. >> yost's life is now largely confined to this cell, he shares with another inmate. >> i'm not comfortable like this. i don't like men. i like women. and to me it's disgusting. i'm still irritated. if i wake up in the morning, i'm agitated because i have to live with another man. >> now the closest yost comes to female companionship is his tattoos, some of which too graphic to show on television. >> that's all i dream about. that's all i got. >> i remember when we met aaron, the man was absolutely tattooed. just incredibly inked. if one word describes him, it's intense. just full of energy. i remember when my producer asked him, what's the daily routine. he started right in on telling us what it was all about. >> one

. >> at kern valley state prison in california, we met inmate aaron yost. who participates in another illegal, yet very common, practice behind bars. tattooing. >> mine's artwork. i mean, i did this myself. >> where. >> huh? >> where. >> in a cell just like this. >> how? >> how? see this cassette player? got the motor out of it. attach a pin to it with the needle. spin a needle on the can, go back and forth. i'll make the ink. i'll burn plastic and baby oil. soot will come up. i'll collect the soot. mix it with shampoo until it's thick, black ink. >> tattooing in prison is illegal and poses a variety of health risks. but we've met countless inmates who have gotten their ink both on the outside and inside. many tattoos represent gang affiliation and are documented by prison officials. most of the rest have a meaning all their own. >> what my trip is is physics. my tattoos represent it. on my back of my legs it says quantum physics. i got an atom on my hand. i study what the ultimate nature of reality is. it soothes me. it soothes me to try and figure out wha

. >> today castellanos is concerned about a white inmate named aaron yost. >> watch out for this guy on the yard. he's calling the shots on the block for the whites. we're expecting something today, but we don't know. >> before coming to prison, yost was a drug addict with a burglary and attempted burglary on his record. when he was arrested for manufacturing methamphetamine in 1996, he fell under california's three strikes statute and got 35 years to life. >> that means i might possibly be eligible for parole in the year 2028. but i'm like 43 right now, and that's a lifetime away. it's an insane -- it's an insane, incredible amount of time to sit somebody who has no history of violence. i don't have any violence on my record at all. none. >> but since coming to prison, yost has been repeatedly written up by the staff for violent behavior. >> it's predatory. prison is predatory. your necessities and your wants, right, run on a razor's edge, you know? when -- it's just an analogy, but when a pen all of a sudden has the value of a corvette, you'll live and die over it. >> for the past