Transcript for Man found dead, believed to have committed suicide with antifreeze: Part 1
This is Stacy castor. My husband didn't show up to work this morning, I don't know what's going on. I'm getting a little concerned because I haven't talked to him since 5:00 on Sunday when he locked me out of the bedroom. Reporter: This story begins with a call to 911. It's a call involving a husband. On that phone is a frantic wife. Her name is Stacy Caston. One of the things Stacy was concerned about was David had a shotgun under his bed. She was worried that he might have committed suicide. I bang on the door. Don't get any response. I kick the door in. Walked into the bedroom. And I observed David lying on his stomach across the bed. It was really an incredible scene. They find David Caston, the husband, on the bed. No clothes on. And he's dead. Stacy was just crying a lot. I mean, distraught. Physically upset. You could see that she was struggling with her emotions. David castor was Stacy castor's second husband, her knight in shining armor. She has two daughters, Ashley and brie, who are teenagers, from a previous marriage. And he was married once before, too. And has a grown son. David Jr. For both David and Stacy, this was their second chance at happiness. And their friends were really rooting for them. David and I had a very good relationship. There wasn't fighting? There's no such thing as a perfect marriage, and we had our share of issues that we dealt with. And obviously being a blended family, it made that much more to have to deal with. Reporter: August 2005. David plans an anniversary trip but Stacy says she didn't want to leave her daughters behind. David got upset, took the bottle of southern comfort, went into the bedroom and locked himself in, and reportedly got drunk. Wouldn't come out. He wasn't sleeping. He was actually in the process of dying that weekend. On the night stand next to the bed was a short glass half full of a green liquid. Another glass that had some remnants of some juice. An apricot brandy bottle. There was a cranberry juice bottle there too. Then underneath the bed there was a bottle of antifreeze that was on its side with the top off. I remember standing in the kitchen and speaking with one of the members of the sheriff's office. Had observed a Turkey baster in the garbage can. And I noticed that it's got droplets inside it. So I pick it up. And I pull the rubber ball off it and I smell it. I can smell alcohol in it. I know he's been drinking. I know alcohol's involved. I know antifreeze was involved. People have committed suicide in the past by drinking antifreeze. It's not a pleasy to go. Stacy had told me that David had been depressed because he had recently lost his father and that possibly his drinking and suicide that weekend was as a result of him being depressed about his father's death. This case could very well have closed and ended and everyone would have thought that David castor killed himself. This was a suicide. But for people who knew David castor, suicide, it just didn't make sense. I can tell you right now, very rarely does anybody commit suicide naked. When you find a body naked, oh, no, start running the lab tests. We started sending in the physical evidence, the antifreeze bottle, the apricot brandy bottle, the glasses, to see if there was any fingerprints or DNA evidence on those items. The glass actually had three fingerprints on it. That jumped out at us was the Turkey baster. It turns out that there was antifreeze inside that Turkey baster. One of the other puzzling things was DNA was on theip of that Turkey baster. They're staing to get even more and more suspicious of what Stacy's motives are. The investigators now start to focus in on, how did David really die? And if it wasn't a suicide, then somebody must have killed David. So it all starts unfolding. And it all starts to even raise more questions for this detective. He wants to interview Stacy castor's first husband. Has anybody interviewed that guy? No, we haven't tracked him down. Well, it turns out we can't talk to him because he's dead. Michael Wallace was buried in a cemetery, and in that cemetery it was his headstone. She had a headstone that would be for her someday. And right next to them was David's headstone. It was very odd and very peculiar. We decided to take a harder look at Michael Wallace's death. Exhuming a body years later is very unusual. It's not like investigators go around to graveyards every day and dig bodies up. Not many judges are going to let you dig up a deceased person just because you have a whim. But we were able to convince the district attorney that this was indeed a homicide of David castor, and we believed that Michael Wallace met the same demise. A few days later I was walking through the criminal investigations division when I received a phone call from the medical examiner. And he said, hey, we just got done with the autopsy, have the results for you. Said, guess what I found? He's loaded with crystals. When you are poisoned with antifreeze, crystals form in your organs. And they don't ever go away. And that was one of the reasons why we exhumed him was so we could find out if thosestals were still there. I knew at that point we had a double homicide. Stacy castor probably killed both her husbands. That's when we said, we need to bring her here for a second interview. A detective Spinelli and I drove out to speak to Stacy. I said, Stacy, there were two glasses sitting on the night stand. You say that you P him some cranberry juice at one point, right? She said, yes. I said, I'm going to show you a picture of those two glasses. I asked Stacy, do you remember which glass it was that you poured the cranberry juice in? And she looked at it and said, well, when I poured the anti-free -- then she stopped and said, I mean the cranberry juice. Like she realizes what she's just said. I said, you said anti-free. She said, you know, I don't like this, you're trying to frame me, you're trying to pin this on me, I'm done. And she stopped the interview. We decided the next step would be to obtain a wiretap on Stacy's phones. And it scares the living Out of me, because I didn't do this. Stacy in that week making a lot of calls. She was in distress. They think I did this. And I don't believe for one secondhat they found antifreeze in Michael's body, I don't believe it. She tells me, they exhumed your father's body. And I didn't believe it. So I went out and checked. I startedcrying. I got upset. Like, he was resting peacefully, and they just dug him up. Why would they dig up daddy? Ashley has just graduated high school, and she's just entering college when she gets this news. Two investigatorshow up and deliver her the news that her father didn't die of aeart attack, he died of antifreeze poisoning. Hello? Mommy, they came to my freaking school. They came to your school? Are you okay? I'm going to be okay, but I'm really freaking out right now. And you can hear it in her mother's voice too,his disbelief that they've come to the school and that they've told her daughter this. And then Stacy castor, the mom, has this suggestion. You know what? This is all too heavy, why don't we drink, why don't we have a drink? Stacy mixes this probably 12unce plastic cup. Ashley, caught up in the moment, this is so cool, this is neat, I want to make my mom happy. She drinks it. And becomes argic. And eventually passes out. And winds up in her bedroom. She wakes up, got a little hangover, goes back to school, comes back, mom again says, let's drink. This time, let's get really drunk. And this time Ashley says, mom, it's not even noon yet. She says, it will be noon by the time we're drinking. But THIT just a second day of mother and daughter drinking. This was actually the scene that would now lead to the second phone call to 911 from Stacy castor about an emergency playing out in her home. I need an ambulance at wetzer road. She's having trouble, I think. It sounds like there's something in her throat. Ashley? Oh my god, oh my god, oh my god.
This transcript has been automatically generated and may not be 100% accurate.