Investigators searching for the 22-year-old's killer recover a selfie on the victim's phone found in a flooded basement, eerily taken moments before she was killed: "I don't think she knew she was in any danger. Watch our all-new 20/20 - TONIGHT, Oct. 9th at 9/8c on ABC. Stream on Disney+ and Hulu (S49, E03). #CatiBlauvelt #ABC2020