COLUMBIA, Tenn. (WKRN) – The sister of a teenager who is the focus of a nationwide AMBER Alert says she believes 15-year-old Elizabeth Thomas made the choice to run away.

An AMBER Alert was issued Monday, March 13, 2017 for Elizabeth Thomas who was reportedly taken by her former teacher, Tad Cummins, who is also charged with having sexual contact with her, in addition to one count of kidnapping. Cummins was added to the TBI’s Top 10 Most Wanted list on March 17, 2017.

WKRN in Nashville spoke with one of Elizabeth Thomas’ older sisters.

“She’s a smart girl and I don’t believe she’d do something like this unless there was a motive behind it,” Brandy Landauer said. “Happy kids don’t run away from home, and if she was unhappy, that could’ve been the reason why she left.”

Landauer is Elizabeth’s older sister by four years. She says she and Elizabeth used to play guitar together and practice for church choir.

“She was a little spitfire,” Landauer said. “Elizabeth was fun to be around, she likes to joke, she was a great singer – I loved to hear her voice.”

She says she, her sister, and their eight brothers and sisters had a good childhood.

Landauer says up until November 2015, she and her siblings were home-schooled, but they played sports and went to church three to four days a week.RELATED: Teacher seen kissing missing Tennessee student, says lawyer

In November 2015, their mother, Kimberly Thomas, was charged with child abuse. She moved out of the home.

Landauer was not far behind. She married her boyfriend, they moved into their own home, and they had a baby.

The 19-year-old older sister defends her mother and says there must be a reason why Elizabeth was running away.

Now, she just wants her home.

“I just wish that she would come home because what she’s done can be forgiven. It already has,” Landauer said through tears. “And if she would just come home everyone would just accept her back as if nothing ever happened.”

Landauer worries that Tad Cummins will get desperate and hurt Elizabeth. She prays that’s not the case.RELATED: Wife of teacher who kidnapped student pleads for husband to turn himself in

Neither of them have been seen or heard from since Monday, March 13. The TBI has said they’ve received hundreds of tips but none have given any credible leads in the case.

Cummins has been charged with Elizabeth’s kidnapping in the case and also faces one count of sexual contact with a minor out of Maury County. He’s accused of kissing her at school.

Thomas is a 15-year-old white female, with hazel eyes, stands 5 feet tall and weighs 120 pounds. She was last seen wearing a flannel shirt and black leggings.RELATED: Tennessee family pleads for missing teen’s return

Cummins is a white male, who stands 6 feet tall, weighs approximately 200 pounds, and has brown hair and eyes.

He is believed to be armed with two handguns and driving a silver Nissan Rogue with Tennessee tag 976-ZPT.

There is a $1,000 reward for information leading to his capture.

The TBI would urge the public to remain vigilant and report any information that may prove beneficial in the ongoing search to 1-800-TBI-FIND. If you spot the vehicle and can verify the license plate to be TN 976-ZPT, call 911 immediately.