Transcript for Karl Karlsen convicted of first-degree murder in 1st wife Christina’s death: Part 10
This was not an accident. It was intentional. And we want to go to trial. My mom never stopped believing. She believed from the very beginning that the trial would actually occur. And she's got a very strong faith, you know, and ultimately she was right. The trial took place in calaveras county superior court, approximately 29 years, almost to the date, after Christina Karlsen died. It was heartbreaking to see my dad in the courtroom. He turns and looks at me and smiles, just a normal dad looking and smiling at his daughter, and it brought back all of these emotions. Christina alexander-karlsen was so many things to so many people. The defendant, through cold and calculated measures, extinguished the light that was Christina. And he did it on purpose. The prosecution scores a early victory by convincing the judge to allow them to tell jurors about the previous incidents and all the insurance payouts to Karlsen. I'd say it was absolutely foundational to the setup of their case that the jury know, not just about the death of Christina, but about the barn fire, about the car fire, about the death of Levi. So when he says, who could do that? Who could kill their wife that way? Well, we already know you killed your son that way. Karl has a conviction in new York for the murder of his son. I can't argue against that and I wouldn't try. You're not here to determine whether he's a good and pious man. That's not your job. Your job is to determine if the people have proven beyond a reasonable doubt that Karl killed his wife and that he did it for money. The first person on the stand was Erin Deroche. She knows what happened. She knows what her father did to her mother. She could speak so clearly about the moment that everyone was evaluating. I testified about his behavior after getting us out of the house. Then, of course, for the few days following the fire. She brought memories of her confronting Karl after his arrest in the death of Levi. It doesn't get much more damning than someone who's supposed to love you unconditionally says, I believe he killed my mother. I know he killed my brother. I was very nervous to testify. I've never participated in anything like this before. And it was on the stand that Colette tells jurors this chilling story about the very first conversation she had with Karl Karlsen after learning that her sister had died in that fire. I went into the house, and I told him that I wanted to see my sister and he said, you she's a crispy critter. That was his term, a "Crispy critter." Everybody in the courtroom just kind of sucked in their breath. I think he truly believed that my sister had burned up in the house and that there would be no evidence. And he was wrong. But some of the most critical testimony came from that fire investigator hired by the insurance company, Ken Buske. The trouble light didn't ignite this. None of the appliances in the home ignited this. It had to be a person applying a flame to the kerosene. Though Karl Karlsen barely spoke in person during the trial, the jury heard him a lot. They heard recordings that were made over the course of his lifetime regarding the investigation into Christina's death. Your not proud of getting money from someone's death. Not proud? I'll tell you where pride comes into it. You break that Wall down and you Save her. Yeah. Ladies and gentlemen, the defendant had motive. His motive in this case was greed. Greed. The defense was questioning the validity of what happened. We all know that that evidence is 29 years old. The defense's argument seemed to be that if the case wasn't strong enough back in 1991, what would make anything different now? This case was ignored 29 yearsing. It was brought to them. He looked at it. They said, no, pass, there's nothing here. I was looking forward to it being done with, and it was the end of week three when the jurors were finally able to go into deliberate. I really thought this would drag out much longer than it did. But the jury came out, said they had a verdict. We the jury find the defendant Karl holger Karlsen guilty of murder in the first degree. Karlsen had no reaction at all. Stone cold. In fact, it looked like he almost expected that verdict. I've never been more humbled by or grateful to 12 strangers in my entire life. It was everything I wanted. He very stoically stood up and he walked away. I really wanted to see him look over his shoulder, make eye contact with those two girls, and just by eye, tell them something, say something to them. Never looked back. He walked away on their mother, walked away on their brother, and he just walked away on them. Again. But before Karl would walk away for good, there would be one more unbelievable twist in this case that, it's almost impossible to believe. I mean, who would take out a life insurance policy on little girls?
This transcript has been automatically generated and may not be 100% accurate.