On Dec. 6, 1991, just before midnight, an Austin, Texas, police officer reported a fire at a yogurt shop on the north side of town. Inside authorities found the burned bodies of four teen-age girls: Eliza Thomas and Jennifer Harbison, both 17, who were store employees; Sarah Harbison, Jennifer's younger sister, 15; and Amy Ayers, 13, who had stopped by to visit at closing time. The girls had been shot. The case consumed the Austin community. Since then, police have searched for the killers and hit numerous dead ends along the way. Over the years, there were dozens of suspects. Correspondent Erin Moriarty reports on this long, difficult case.