"We have a 15-year-old girl with a 50-year-old man and he obviously used his power, his authority to, whether it's groom her or convince her, to do certain things", the girl's sister-in-law said.
Authorities credit the caretaker of the remote Northern California property for helping police find the girl.
U.S. District Court Judge Kendall J. Newman ruled Tad E. Cummins is a violent danger to society and a flight risk.
Meanwhile, Elizabeth's alleged abductor has been detained in California's Sacramento County jail since Friday.
Tad Cummins, 50, allegedly altered his appearance, switched license plates twice, disabled the car's Global Positioning System and used various aliases for him and the teen, documents state.
Authorities received a tip late Wednesday night that the pair may have taken up residence in the woods in Siskiyou County, perhaps for more than a week, bureau spokesman Josh DeVine said. The pair went missing on March 13.
He said she is happy to be back and is in good spirits, enjoying some of her favorite food, but she is just now learning about the nationwide search for her.
Whatley said the family now wishes to step back in privacy, saying it is time to focus on the teen and her recovery, "which could easily take an extended period of time... at this time they must ask for privacy as they navigate these very important next few weeks and even months".
While Elizabeth Thomas got re-acquainted with her family and friends, the complications in her family's domestic case continued.More news: Red Sox ban fan from Fenway for racist taunt
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Documents also revealed that Cummins fled Tennessee because he was anxious an investigation would ruin his relationship with the teen.
The father of Elizabeth Thomas filed a restraining order against her mother, his wife, on Monday.
For his own safety reasons, federal authorities would not disclose what day Cummins will depart California or when he will arrive in Tennessee. If convicted of the federal charge, he faces at least 10 years in prison, acting U.S. Attorney Jack Smith said.
Anthony tells PEOPLE he is anxious about how he will react if he is in the same courtroom as Cummins: "I'll become emotionally charged and, yeah, I'd like to do to him ... what every other father would like to do in the same situation".
Elizabeth Thomas and Tad Cummins were found in a cabin in California last week.
Cummins, who was the girl's teacher before being fired from his high school, is charged with taking a minor across states lines to have sex.
Cummins is facing a federal charge of transporting a minor with intent to engage in criminal sexual activity. "We'll make sure she'll get what therapy she needs and that she's safe, that she knows she's safe".
Kat Bozeman, Elizabeth's sister, has recently given an interview with WKRN regarding her family's ordeal.