like, "what in the world's goin' on?" >> reporter: and despite the tension during the marriage and divorce, those who knew brooke best didn't think her ex-husband was a killer. >> i just never entertained that thought. >> clayton was a good person. so i didn't think that, you know, he would be capable of doing something like that to brooke. >> reporter: more importantly, clayton's alibi checked out. investigators cleared him. if not the ex-husband, then who? who had brooke come in contact with that weekend? investigators retraced brooke's steps, starting not with the game on saturday, but with the night before, friday. friends told investigators they had tickets to a concert. >> she was super excited about going to that. so she was just, like, "okay, i've gotta go -- i've gotta go find something to wear. i'm gonna go to dinner." >> reporter: after dinner, brooke left her car in a shopping center parking lot near the restaurant, and drove with friends to the concert. she spent the night at dina's house. >> i called it hotel dina like everyone just stayed.