For as long as she can remember, Heather Thiel believed her father was a killer.

She was so convinced that she twice urged authorities to examine whether he was responsible for a horrific, unsolved double murder that shook rural Wisconsin more than three decades ago.

But her role in the investigation into the slaying of Tim Mumbrue and Tanna Togstad led to an outcome she never could have imagined — three years ago, authorities concluded that her cousin, not her now-deceased father, fatally stabbed the couple on March 21, 1992.

For more on the case, tune in to "Raising the Dead" on "Dateline" at 9 ET/8 CT tonight.

DATELINE FRIDAY SNEAK PEEK: Raising the Dead

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Just as head-spinning, that cousin, Tony Haase, was acquitted in the murders earlier this year. During a nearly monthlong

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