convicted of sex offenses and just about any one of them could have done something like this. >> rex krebs is one of dozens of sex offenders interviewed by police. he and hobson have been talking for weeks, informally, at the county jail. since krebs' parole agent notifies the task force there's a parallel between the way the women apparently vanished and the suspect's past. >> back in may 1987, he committed a rape. he had broken through the bathroom window. and at the end of that crime, he hog tied the victim and left the residence. i'll never forget this. he said to the victim, have a nice day. >> krebs served ten years for the rape as well as another sexual assault. now investigator hobson believes it's time to interview krebs on camera hoping to extract a confession and find the college students. rachel newhouse and aundria crawford. >> if you were going to do that crime, and you saw somebody you wanted to abduct -- bear with me here, this is a hypothetical -- that you wanted to abduct and take someplace, how would you do it? >> i'm not even going to talk about that. thinking like that