The search for a missing Maury County teen and her alleged captor has escalated as investigators continue to learn and release more information about the pair's relationship.
The working theory for investigators is that the suspect carefully groomed her and then brainwashed the teen into abandoning her family to be with him.
Elizabeth Thomas, 15, was last seen in Columbia Monday morning at a downtown Shoney's, and it's there that the TBI thinks she met up with her teacher, Tad Cummins, and disappeared.
The FBI joined the investigation on Thursday.
"They are being more elusive than we expected so the FBI is bringing in their experts -- behavior science people," said District Attorney Brent Cooper who will prosecute Tad Cummins when he's found.
But with no credible sightings of the 50-year-old his student yet, the FBI has gotten involved. They are looking for leads and will profile Cummins
"I don't think there is is any doubt there was planning and forethought put into this," said General Cooper.
Security video released by the TBI shows Cummins filling up his silver Nissan Rogue at a gas station next to the Shoney's Monday morning.
Thomas, who appears to have willingly joined him, may have already been in the car. She comes from a family of ten children. Her mother is currently facing felony child abuse charges.
General Cooper called the teen a vulnerable child. "She's had incidents in her life that made her situation much more difficult," said General Cooper.
The TBI believes Cummins groomed the teen. He allegedly posted romantic Instagram messages for her to see. Then agents said he armed himself with two handguns, which is a concern, and vanished with the girl.
"He's done something incredibly stupid and potentially dangerous," said General Cooper.
Sources close to the investigation said there's little doubt Cummins is manipulating the girl. He's even allegedly told her he is some type of secret agent like Jason Borne to win her trust and get her to willingly accompany him.
So far, Cummins has been charged with only a misdemeanor.
Many have wondered why he's not charged with felony kidnapping? The District Attorney said it appears the 15-year-old went with Cummins willingly.
"It's kidnapping if the child is 13 or under, but no provision for a child 13-18," said General Cooper.
Cooper planned to discuss changing that with state lawmakers
Meanwhile, the TBI has acknowledged the couple could be anywhere in the country and have issued a nationwide BOLO to look for them.
Anyone who see them is asked to immediately call police.