surrounded by friends and family, then moved east after joining the army. she had a job she loved, a baby daughter she adored and her whole life ahead of her. then she was shot dead in her home. her killer thought he'd covered his tracks. but investigators were determined to follow the clues, exposing a plot so devious it defied imagination. here's andrea canning with "the alibi. " >> mommy. >> reporter: across the spectrum of love is there any more precious than that of a mother for her daughter?? you are my sunshine my only sunshine? our story is about that maternal tie that endures from generation to generation. it begins in a military town near the mexican border. del rio, texas. a small city anchored by the laughlin air force base. karlyn ramirez grew