. >> everything kept coming back to nicholas holbert as the prime suspect. >> so investigators dug intor disturbing. >> he was a registered sex offender and served time in a penitentiary for that. >> it certainly was a red flag, the fact that he had a prior sex offense and he is the last person that's seen with kelli. that was very, very concerning to us. >> the da didn't have any evidence to arrest holbert for kelli's disappearance, but he did discover holbert was violating the terms of his parole. >> he was a prior sex offender, and he was not registered properly and he was placed in jail. >> sex offender nicholas -- >> right where detectives wanted him. now they could watch holbert, see if he blabbed to a cell mate about what happened to kelli. they also questioned him twice, even took him back to froggy bottoms to jog his memory, but holbert stuck to his same, though sometimes inconsistent story. >> you caught him in lies but you couldn't crack him? >> exactly. >> by now olivia and matt had left fayetteville and gone home. you must have felt kind of like you were leaving your sister