Transcript for Family of ex-teacher accused of kidnapping teen says they forgive him
Tonight, the emotional interview with the family of the teacher on the run specced of kidnapping an underage students. His wife and two daughters thought they had an ideal family life. The illusion was shattered and they're pleaing for him to turn himself in. I go from feeling so hurt I can't even function. It's very selfish of him to have done this to us. Reporter: To Jo Cummings, complete betrayal. Her husband, 50-year-old tad Cummings, accused of kidnapping student 15-year-old Elizabeth Thomas and having an inappropriate relationship with her. Then sometimes I have this peace that comes from god. I do love him but I don't trust him anymore. He's totally betrayed me. Reporter: He's been on the run from police for the last month. They were last seen shopping at this Oklahoma Walmart two days after they disappeared. No matter where you are, daddy, no matter what you've done, we just want you to come home, we miss you so much. Reporter: Tuesday Cummings' wife and two daughters are speaking out exclusively to ABC news in an interview with Eva pilgrim. There's two sides. The world's heard her side of it. There's always be some on the other side of the amber alert. The amber alert, it's for both of them, he's a missing person just as much as she is. He's very important to a lot of people. When you realize that your husband of 30-plus years kidnapped a 15-year-old -- I think she went by her own choice, but I don't think she was old enough to make that choice. I don't think he forcefully took her. She was manipulated by him. Reporter: Jill says she thought she had a storybook 30-year marriage. But just a few months ago, police say tad was secretly searching "Age of consent," and how to marry a teen. What was your marriage like? We were together all the time. We'd go to work, come home, eat together, do things with our family, go to church, go shopping. Reporter: That is, until one day last month when Jill came home to find a note left by her husband. Tad, this is not you. Reporter: She called the police. I found out that she was also missing and that was when I knew. That was the moment that I new. When you heard that she was missing, why did you immediately think they were together? Because it made sense then. For the first time. Did you realize all of a sudden that he had been lying about everything? At that moment, then I knew. That it was all a lie. Reporter: Jill says she thought tad was mentoring 15-year-old Elizabeth. She had been spending time at their home prior to their disappearance. You said you thought he was helping Elizabeth. Right. What did you mean by that? She would come to him with her problems about her past. She always asked him, why do bad things happen to good people? He was trying to help her to work through those feelings and those problems. I think he was mentoring her and maybe just one bad decision started him off on a path he didn't mean to go on. You look at Beth like a third daughter? Yes. Hard to believe now. Why? That's just the way we felt. I mean, somebody we were helping, you know. Reporter: His family painting a picture of a devoted Christian father who now seems to have been living a double life. Allegedly infatuated with this teenage student. He was always happy. Was he really involved in your lives? We had a very close family, very happy upbringing. Everything was perfect. We had a wonderful, perfect family. What they said I thought was not painting him into a dark place or a dark corner, trying to be very positive and open. All of those things I think are exactly the right things to try to hook him to say, look, you need to come back. Reporter: The first signs of trouble happened months earlier. School officials began investigating the health science teacher after another student claimed to see them kissing in his classroom. Cummings denied any wrongdoing but was later suspended. I didn't see this coming at all. You send your kids to school, you know -- you trust they're going to be all right there. He is a predator. She does not have any will of her own as we understand it. She is under his spell. And she's being controlled by him. Reporter: Ashley and Erika last saw their father the weekend before he went on the run, allegedly taking 15-year-old Elizabeth with him. He was at my house Saturday night before they left. He came over to see our newborn. We just hung out on the couch and talked. Just a Normal night together. I work midnight, so he had watch mid son with my mom the day before. Reporter: His former student, Elizabeth Thomas, was seen being dropped off early the morning of March 15th at a restaurant in Columbia, Tennessee. But before she left, her sister says Elizabeth woke her up with a warning. She said, if I'm not back by 6:00, you need to come find me, call the cops. Reporter: A short time later this security footage showing him filling his SUV at a nearby gas station. Days earlier he took out a $4,500 cash loan. Sources telling ABC news Cummings researched camping and SUVs and watched a TV show about living off the grid. Hours after that gas station surveillance footage from Monday, Elizabeth Thomas is declared missing. Last clue, a cell phone ping from Decatur, Alabama. Days after the pair turn up on video at a Walmart in Oklahoma City. The problem with that video is law enforcement didn't even know about the video till maybe two weeks after it was captured. So two weeks cold on a camera shot like that -- really puts you behind. Because then where do you go from there? You're in the middle of Oklahoma City, Oklahoma. Right in the middle of an interstate system that goes virtually all four directions. Reporter: But the video does reveal small changes to their appearance. Elizabeth's hair, darkened red. Cummings' gray facial hair brown. Investigators say the pair bought food, paying with cash. Why walk into a Walmart of all places? The average person knows Walmart's got some of the better camera systems in the country. Reporter: While authorities say they don't know where Cummings was planning to go they say he packed warm weather clothes, shorts and t-shirts for the trip. After a month on the run, he likely will need a refill on his blood pressure medication. More than likely that if he goes into a pharmacy or a drugstore, it's going into that location that might get him caught. Reporter: The former teacher now on Tennessee's top ten most wanted list. What would you say to her family? I'm so sorry, to her family. I know they've got to be hurting and scared. And I'm just -- I wish I could fix it. Reporter: The Cummings family is hoping he will return. I hope that he realizes that we're still here and that it makes him realize that if he comes home, that he's not coming home to nothing. And that maybe it will make him decide to turn himself in. You just want him know you guys are still here? Yes, for sure.
This transcript has been automatically generated and may not be 100% accurate.