The father of 15-year-old Elizabeth Thomas believes her former teacher Tad Cummins "groomed" her for months before authorities say he kidnapped her in mid-March.

Grooming is a common term for child welfare advocates, and a term used a lot in the past few weeks as officials worked to bring Thomas back home.

Child advocates say they see predators "groom" their victims by taking incremental steps to normalize inappropriate behavior with the child. The more vulnerable, the easier to groom.

Christina Copeland, a forensic interviewer at New Hope Blount County Child Advocacy Center, has worked with child abuse victims for nearly 20 years. She says grooming is a common element in most child abuse cases, which normally involve victims who know their predators.

"The purpose is to desensitize," Copeland said. “The person who is doing the grooming is trying to gauge how they’re going to react – are they going to tell somebody? And to give them situations that are just a little bit out of the norm.”

She says predators will often then manipulate victims into thinking an activity was their idea.

“And then that limits the number of people that you can tell about it because you don’t want to get in trouble," she said.

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Lt. Brad Anders is with the Knoxville Police Department’s Special Crimes Unit. He works with the Department of Children's Services and other local, state and federal agencies on everything from missing person cases to child abuse and human trafficking.

"They'll just find someone, figure out what they're missing, and then try to fill that void and to develop a relationship,” said Anders.

With more public awareness in recent years, Anders has also seen more reports of abuse and, subsequently, more arrests.

"Now that we have TBI, FBI and the locals all working together on this, I think it's going to make a difference,” he said. “Our goal is for Knoxville to not be somewhere people are trafficked, but we have two intersections that come together where you could be anywhere in a day.”

Both Copeland and Anders agreed social media has made grooming faster and easier for predators.

Child advocates advise staying aware of what your kids are doing online. They also suggest keeping communication lines open with children and letting them know they will not face punishment for their honesty with you.