Dateline Trailer: Who Killed JonBenet?

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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, 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.