with her family, comes forward to the police with a secret that breaks the case wide open. >> deann schultz, one of our sisters, as we considered her, and that was something that we never, ever suspected. >> in this home video, deann seems to be really a member of the family. >> here's deann. say hi. aunt deann. >> and yet, we know that she's very, very close to one of the great betrayals. >> the last week that donnah was at our house, she told me that deann and her husband were having marital problems. and she said that mark was helping to guide them. he was going to help be the mediator that brought this marriage back together again. or so donnah thought. >> deann schultz also stated that prior to the murders, mark made a number of incriminating statements. >> she tells them that he said things like, it would be easier for us to be together if donnah just died. all you'd have to do is come in and find the body. >> deann stated that she declined to participate in that. after mark learned about the trip that donnah took with roger harrington, he told deann, i've got to get that driver in my