in fact, she moved into a house owned by one of the nursing professors. this woman, charles knell lee. was she a good? tennant >> oh,. yes like, the best. >> spit spot all the time. >> always. yeah, she was awesome. >> just around the time china was heading toward a breakup with her husband, billy. billy was also a nurse, maybe a mentor, of sorts, to cassie. he seemed to be very fond of her. saw her a lot, at work, around the house. then, pretty soon, a serious boyfriend came along for cassie. david barry. >> he was wonderful with the children, and that was something that she really liked about him. >> casey's friend and coworker, mary flores. >> they had a relationship that was fun. they were just building a life together. >> especially on the morning of march 24th, 2014. something billy lee had been