>> definitely it was all intermixed. >> reporter: daron wyatt was promoted to detective sergeant and his caseload shifted to other types of crime. but he never forgot his promise to mary. in part because of a milestone in his own life. >> my first daughter was born. and i remember going to mary shortly after that and looking her in the eye and saying, "i know -- i know now how you feel. i know it. i can feel it myself. i'm a dad now. you haven't given up. i won't give up." >> reporter: in 2003, nine years after the murder, daron once again approached a friend in the d.a.'s office. >> i said, "i've got a cold case that i need you to take a look at." and he physically stops walking and he says, "if it's the case i'm thinking about, i'm not going to touch it." >> reporter: but daron was persistent. eventually he persuaded his friend to take cathy's case back to the d.a.'s homicide unit. the same unit that had rejected it twice before. this time though, something different happened. a prosecutor unfamiliar with the case agreed to take a fresh