Transcript for What former FBI agent, daughter say happened night of her husband's death: Part 2
"20/20" continues. Once again, Lindsay Janis. My name is Tom marten. Reporter: In the earlt hours of 2013, Mr. Marten makes a stunning call. A baseball bat It was Saturday. The kids had birthday patients. Reporter: Molly's parents were never supposed to be with their daughter that day. They make a fateful decision to drive over and visit for the night. Were they welcome in the home? I knew they didn't feel comfortable in the home. But they knew it was beneficial. The martening arrive bearing a gift for jack. I brought over a baseball bat for jack. He thought it was really cool to get any former baseball gear that was a hand me down. Reporter: After pizza for dinner, everyone settles in for the night with Tom and his wife in a guest room and Molly and husband on the first floor. 3:00 A.M., Molly acawakens to a sound familiar to any parent. Sara woke up. She came down. And the kids were not supposed to come in the room and wake up Jason. So they would stand outside of the door and whisper until I heard them. Reporter: She says she get 8-year-old Sara back to bed before tiptoeing to her room. He woke up and was angry and I told him Sara had a nightmare and he was just furious because Sara had been doing this lately and she wanted to be coddled and she was too old for that and I shouldn't have gotten out of bed. Reporter: She says it gave her courage to stand up forself. She is 8. All she wanted was her mom to lay with her a couple minutes. And he forget my parents were there. I don't know what woke me up. What I heard were loud voices and I heard a thumping. So I grabbed that little league baseball bat and I ran upstairs. He wanted to shut me up so I covered my mouth and he started choking me. At some point, he stopped and I screamed. The next thing I remember is my dad standing in the door way. Reporter: What did you see? It's awful. He has his hands around her neck and he quickly moves to move her in front of him, between me so he's got her in a choke hold. Fear was secondary at that point. I was so ashamed my father would see me like that, allowing myself to be treated like that. Reporter: Did you know your dad had a bat with limb? I don't know that it rege step right away. I said let her go. And he said I'm going to kill her. I said if he gets the door between me and him, she's dead and there's nothing I can do about it. So I reached around and I hit him in the back of the head with the baseball bat, and what happened when you hit him? If he could have gotten angrier, he did. Reporter: Tom said it didn't stop Jason. He kept dragging Molly to the bathroom. He made it to the bathroom. I'm in the bathroom with him. And I hit him again. I mean, I have room now, and I hit him hard. Back of the head again. Reporter: You hit him hard? Yeah, I did. He still got her by the throat but he changed his tactics. He decides to come back at me. And I'm swinging the bat. And he catches the bat in his hand and he sends me flying across the room. Jason just grabbed the bat away. He could choke me with one hand and grab the bat with the other. He was just so much stronger. And I was screaming, don't hurt my dad. Don't hurt my dad and I thought he's going to hit my dad with the bat and kill my father. I get up and grab the bat and hang on for dear life. I'm trying to hit him with the bat or elbow. I'm going to hang on to that bat and he goes down. Reporter: He went down. He went down and I realized, okay, he's not going to get up. Looks like the threat is over. Reporter: This version of events will eventually be challenged. What we know is aren't 3:00 A.M., Tom martens makes this call to 911. What's going on? He's in bad shape. We need help. What do you mean he's in bad shape? He's hurt? He's V he's bleeding all over. I may have killed him. It hit in the head. With what? A baseball bat. Yes, ma'am, he said I'm going to kill her. The 911 dispatcher instructs Tom to give cpr to Jason. He hands the phone to his daughter. I need to you calm down to help him. I'm certified. I just can't think. You have to stay calm. I think he's going to sit up and start choking me again and it was terrifying. Reporter: Did the kids sleep through that struggle and the 911 call? The kids did. And I keep their rooms closed and my door closed bus arguing was a common theme. Reporter: And your mom was down testairs the whole time? My mom was in the guest bedroom. She told my mom to stay in the room with the dogs. Reporter: Ems and police arrive and take Molly and her father to separate patrol cars. I was told. Don't worry, it looks like self-defense. It looks like self-defense. I don't think there's going to be an issue with that. They are photographed and told they are free tlo go. Deputies drive them back to the house about seven hours after the incident. The sheriff was there. He Dade, we're done. Reporter: They were finished processing the scene that quickly. Yeah, they were done. Reporter: But investigators are just getting started. And what looked like self-defense looks a lot like murder. Reporter: They are alleged you finished him off. Did you murder Jason? There's more to the story of what happened that night and it's about to cost Molly her reputation, her freedom and even worse, the children who called her mommy for eight years. I begged and begged, please don't take the kids.
This transcript has been automatically generated and may not be 100% accurate.