Susan Curtis
Susan is from Bountiful, Utah. She was attending the Bountiful Orchard Youth Conference at Brigham Young University in Provo, Utah when she disappeared on June 27, 1975. She'd ridden her bicycle fifty miles from Bountiful to Provo to attend the conference, which was lasted two days. Susan was last seen on the first day of the conference.

That evening, following a formal banquet at the Wilkinson Student Center, she left her friends to walk back to her dormitory and brush her teeth. The distance was about a quarter of a mile. Authorities don't believe Susan ever arrived at her dormitory, because when they checked her toothbrush it was dry.

https://charleyproject.org/case/susan-curtis