Angela Brosso, 21, and Melanie Bernas, 17, were separately killed while riding their bikes along the Phoenix Canal.

These murders became widely known as the Phoenix Canal Murders," says Briana Whitney, the true-crime reporter for CBS affiliate KPHO-TV in Phoenix.

Investigators got a break 21 years after the murders when, thanks to DNA and genetic genealogy, they zeroed in on 42-year-old Bryan Patrick Miller, a divorced father raising his teenage daughter. Investigators soon found out that Miller had an alter ego. He was a local celebrity known for participating in parades and festivals as the "Zombie Hunter," a zombie-slaying comic book hero armed with a larger-than-life Gatling gun.

Detectives just needed a sample of Miller's DNA to make the case or eliminate him as a suspect. That quest took them to a local Chili's.

On Dec. 14, 1991, 16-year-old honor student Sarah Yarborough was on her way to drill team practice at Federal Way High School outside Seattle, Wash. She never made it. She was found murdered just a hundred yards away from her car on the school's campus. Correspondent Natalie Morales speaks to key people who were involved in bringing Yarborough's killer to justice, including the first television interviews with Sarah's family and friends, and a woman who had been attacked by the same man years earlier.