When a nurse is gunned down in her home, detectives initially believe they have a clear suspect, but new information leads them down a completely different path. Josh Mankiewicz reports.

Dateline investigates the case of a young Fairfield, Ohio, woman, 21-year-old Katelyn Markham, who vanishes one summer night in 2011, prompting her community to conduct a massive search. When her skeletal remains are found in Indiana two years later, investigators question her friends and family to uncover her killer, but It takes 12 years and a detective with dogged determination.