i knew it was earon then. >> their daughter, earon harper, 42, was dead in the doorway. >> when you saw that jewelry, you knew it was your daughter, what went through you, judy? >> i lost a son in'78 in a car wreck. he was already gone when i got to the hospital. i could have shed a few tears, went on about my business, but this was different. my son was 21. he had no children. >> the loss of earon, a mother of four, was devastating. but now the family had to deal with what happened to baby erica. finding out in the most impersonal way. >> i knew she was hurt by the police rushing her down the street that i saw on tv. >> and later, they learned how badly hurt. she had been shot in the head. >> why, in the name of god, would somebody do that? >> it was this man's job to find out. >> now, in your experience, how many times have there been babies who were victims? >> there's never been a case where a baby's been shot that i've worked. >> a lifelong local, once promising pitching career at the louisville, he didn't know this would be the case of a lifetime. >> today's date is may 18th, 2006

. >> what you had to battle, i guess she did have her earon's fighting spirit to pull through all of that. you know. so, thank god for that. >> that's all for this edition of dateline. i'm craig melvin, thank you for watching. watching hello, i'm craig melvin, and this is "dateline." >> i'm craig melvin. and this is dateline. >> i can't believe that their baby is lying there lifeless. >> she was everything to me. she was so sweet everybody. >> state troopers said bonnie had died in a hiking accident. >> the said she fell off a cliff. her mother said, they were wrong. >> i was screaming to them, these are defensive wounds. >> no witnesses, no weapon. nothing left behind by a stranger's dna. >> we no longer have some accidental death. this was a homicide. >> they had no suspect. but for years, her mother kept fighting to find bonnie's killer. >> bonnie's mother continues her own crusade. >> then after more than a decade of searching, a phone call. >> i just got information, there was a match. >> can we get a conviction on just the dna? >> and there was something else. something about b