reporter: sharon wouldn t know for a long time the truth about scott s phone call that night, but it was that night after the vigil that privately sharon first allowed her mind to go to that very dark place. i remember it was new year s eve when i started going back and forth, but just to myself. i wouldn t say it out loud. i was afraid to say it out loud. but i started just kind of thinking, could he be involved with her disappearance? reporter: sharon was a frantic mess and she d look at him, and he just seemed so detached somehow. never once did he say, oh, my god. where is laci? no. where could she be? i hope she s okay. i hope, you know, she s not harmed. never, ever you were feeling that panic. even as you talk about it, you can see a little bit of it left. he did not seem to have that sense? he did not have it. and i actually made out a list of, did he or didn t he? i had a list. and there was a lot more on the did than didn t. and that s what really scar
reporter: a week after laci peterson disappeared, they had a vigil. everyone coming together and praying just helps, helps you feel like you re doing something. candles and prayers and tears and though much of modesto was here, in body or spirit, not a single person understood not yet, not for a while, why this gathering would become a defining moment. especially, perhaps, scott peterson. because, though it looked as if he might have shed a tear or two, he seemed to be avoiding laci s family and friends. what about the vigil? he wasn t he wasn t on the stage. no, he wasn t on the stage. no, he was on the phone. reporter: sharon wouldn t know for a long time the truth about scott s phone call that night, but it was that night after the vigil that privately sharon first allowed her mind to