When 16-year-old Theresa Bier didn't show up for school one morning, her friends confessed she had a secret. The teenager had confided in them that she was going on an adventure with an older man in the mountains near Yosemite National Park. But when the man returned to town without her, police demanded to know what he did with her. His answer set off one of the most bizarre kidnapping cases in history. He said, "Bigfoot did it!" Theresa was never heard from again, and the case is still unsolved. CrimeCaster Alysia Sofios uncovers new details and releases clues about what may have happened to the missing teen.