Elizabeth Thomas' older sister, Sarah Thomas, says her sister hasn't reached out to her since she disappeared on March 13. However, Elizabeth appears to have updated her Instagram biography.
"I was hurt. I don't want her even calling herself a wife. She's too little. She's my little sister. She's 15," said Sarah Thomas.
Sarah said she noticed the word "Wife" with a diamond ring emoji added to Elizabeth's biography after she went missing.
Elizabeth disappeared on March 13. The Tennessee Bureau of Investigation believes she is with her teacher, 50-year-old Tad Cummins.
"I can't handle her being gone. It's really hard," said Sarah Thomas.
Sarah said her younger sister woke her up from school every morning, but the last time she woke her up was unusual.
"She looked at me and said 'Hey, 'I'm going to be back at 6. If I'm not back by 6 call the police.' I kept falling asleep and she kept saying 'Sarah, Sarah I need you up,'" said Sarah.
Sarah said she would sometimes find Elizabeth - and other students - in Cummins' classroom at school.
"We went there a whole bunch. That's where all the kids went, and that's where my sister was and she's my best friend," said Sarah.
On Jan. 23, school documents reveal a student saw Cummins and Elizabeth kissing. Elizabeth's father was informed the following week by local law enforcement.
Sarah Thomas said Cummins openly denied a relationship with Elizabeth after that incident occurred.
"He would go on and on about, 'Hey, you know I don't like her. You know I didn't do that with her," said Sarah.
Sarah said the house is quiet without her sister, and she wants her to return safely soon.
"Please turn yourself in and please give back my sister," said Sarah.
Anyone who may have interacted with either Thomas or Cummins before their disappearance should call TBI at 1-800-TBI-FIND. If you spot the suspect vehicle and can verify the license plate to be TN 976-ZPT, authorities say to call 911.