the one for jarrae estepp, the girl on the conveyer belt. ga002ab >> it's bad, it was bad.s bad. >> reporter: strangled, beaten, sexually assaulted. viciously, according to deputy d.a. larry yellin. >> should have been a college girl. >> should be worrying about grades and boyfriends, and football games and -- and those things. >> reporter: one wrong turn, and you never know, huh? >> yeah. >> reporter: but almost three weeks in detective julissa trapp seemed stuck. >> i think she got a little frustrated, and got a little desperate, and came up with the idea of using the computer database. >> reporter: that is the computer database of sex offenders. if they had a serial killer on their hands, there was at least a chance he'd already run afoul of the law at some point. it was a bit like just poking a finger into the haystack frankly and hoping to encounter a needle. but worth a try. so trapp called this woman. sexual assault detective laura lomeli. >> all sex offenders on parole, they will have an et monitor. >> reporter: trapp asked lomeli, were any of those gps monitors her