NBC's Dateline: TAG Expert Ron Walker on JonBenét Ramsey Murder

This year marks 20 years since six-year-old JonBenét Ramsey was found dead in the basement of her family's home in Boulder, Colorado. In a Two-Hour Dateline Special, TAG expert and first responding FBI agent Ron Walker opens up about his experience on the case.  The special includes first-ever TV interviews with former Boulder PD detective Jane Harmer, former Denver PD detective Tom Haney and never-before-seen case documents. Josh Mankiewicz reports.