and they liked her new boyfriend, david berry. >> i thought when she moved in with david, that maybe>> tristan actually started calling him daddy david, which cassy would be like, "you can't call him that. your dad's gonna get mad. " >> and sure enough, said cassy's sister, he did. >> he expressed to cassy that he didn't like it. that the kids better not call him that. >> he blamed cassy for it. >> yeah. >> and a few weeks before cassy's death, she told her parents, son tristan came home from a visit with brad utterly terrified. >> they ask him, "what's wrong, tristan? " he says, "daddy said he's gonna kill mommy and david. " he was 5 years old. i don't think a 5-year-old makes that up. >> by then brad was no longer on the police force. and things weren't going so well for him. when sergeant watkins finished reviewing it all, police reports, his own interviews, what he felt was something like amazement. >> wow. nobody in this world is pointed out as having any reason to want to harm her other than brad. as long as she was alive, cassy had the kids and a new man and a great job. and h