few have done so as dramatically as one of the most memorable murders ever profiled in "lockup," carl abuhl. >> there are people with certain criteria, rapos, child molesters. you kill them. there's no proper problem. >> reporter: he was sentenced to 77 years for killing a co-worker with, he killed again at spring creek. >> why don't you try raping another man. why you raping a woman. rape me. try to [ bleep ] me. i know there's someone out there bigger and badder than me but i'm going to die. i'll die for what i believe in. i have a lot of experience. >> a lot of experience in what. >> doing what i do. >> which is? >> taking out the garbage. >> because they so frequently become the prey of inmates like abuhl, most sex offenders live in protective housing units. that's where we met ray rowe. >> it's a big honor badge for general population to kill somebody, especially a sex offender. >> rowe. >> rowe was sentenced to 230 years for an unlawful act with a minor. >> they don't care whether they're innocent or guilty, somebody said did you know that guy is a chester. >> which is? >> next thing