Several details were missing from the Unsolved Mysteries investigation into the true story of the death and unsolved mystery of Tiffany Valiante. The premiere episode of Unsolved Mysteries volume 3, "Mystery at Mile Marker 45," detailed how the popular student athlete disappeared from a party following an argument with a friend. As her family and friends were searching for her, Tiffany was hit by a train roughly four miles from where she was last seen. The investigators believed Tiffany died by suicide, but her parents came to be convinced that she was murdered.
https://screenrant.com/unsolved-mysteries-tiffany-valiante-true-story-details-missing/