Transcript for Woman David Temple was having an affair with describes their relationship: Part 6
In the small city of Katy, Texas, it's just days after the murder of Belinda temple and investigators are very interested in a rumor that her husband David was having an affair with another teacher, Heather Scott. So after the murder, they brought her in for questioning. Frustrated investigators feel like she's being evasive. She would later be called on that in court. On January 12th, 1999, you were trying to help the police. Yes. Did you tell the police that, for the past three months or so, David and you had been sort of seeing each other? If you listen to the transcript of the interview that Heather gave to police, you can tell why they were suspicious. She was downplaying that she had had a physical relationship with David. "After leaving the bar, sometimes we would come back to my house, sit around, and watch movies." Yes. So that's how you were helping the police understand how intimate your relationship was, that y'all watched movies? Was that a question? Yes. That y'all watched movies, I don't know what else to say with that statement. I'm sorry that it was quick and I didn't give -- Well, you don't have to apologize. If I ever am in this case again. I'm sorry. I will do it differently. But when they do a deeper dive, Heather's emails to David indicate they were doing more than watching movies. This is Monday, November 9th at 1:36. Did anyone ask you guys where you went on Friday? Did you get home too late? I hope you didn't get into any trouble. I don't know if you knew but I was really drunk. I really don't act different except I get more affectionate. Can you explain to me what you were talking to David about, getting more affectionate? That drinking made me more affectionate. And more affectionate with who? I guess with him. Okay. When you asked if he got in trouble, who were you asking if he got in trouble with? I'm assuming his wife. And so you knew he was married? Yes, at that time, yes. Did you know he had a child? I found out, yes. Did you become affectionate with him after you knew he was married? Yes, I did. And after he had a child? Yes. And his wife was pregnant? Yes. David had maintained that his relationship with Heather was casual, not that serious, but yet she testified that around the time of the murder that she and David had professed their love for each other. According to Heather, she said that the week before Belinda was murdered, that David says, "I think I'm falling in love with you." But that doesn't sound like a guy who's casually having a fling with somebody as he portrayed it. Did you go back to your place? Yes. Did y'all have a serious talk? I don't know if it was a serious talk, but that's when he said, "I think I'm falling for you" and I said, "I think I feel the same way." That's in my statement. And what were the words that David temple used? I think he said, "I think I'm falling in love with you." Did that catch you off-guard? I mean, maybe. Yes. But you told him you felt the same way, correct? Yes. Of course the investigators, that was their "A-ha" moment. David was having an affair, so he must've killed her. But that just doesn't compute. There're lots and lots of people that have affairs that don't kill their wives. Were you concerned at all about where that relationship was going when he was married? No. You weren't concerned about that? I wasn't planning on it going anywhere. The picture that begins to emerge for investigators, you've got a cheating husband, a mistress who feels guilty. And they want to be together, but they can't for obvious reasons. But it was complicated, Yes. Because? It was inappropriate. I don't know if complicated is the word. Well, there was something in the way, wasn't there? I'm not sure -- is there a question? Was there something in the way? He's -- Of the relationship getting even more -- It was an inappropriate -- Involved? -- Relationship because he's married. Did you understand my question? The phrasing is awkward to me. Is there something in the way? Was Belinda temple in the way? I didn't think about her or discuss her. I just knew that he was married and it was not appropriate for me to have a relationship with him, but I did it. Did it come to your mind then that things needed to change? Yes, I felt guilty about it. Yes. I just remember having a discussion that our relationship wasn't appropriate and we probably needed to end it. When David temple was first confronted with his affair with Heather Scott, he said it was just physical. It was not serious. But look at the timing. She was murdered January 11th, 1999. June 9th, 2001, he marries Heather Scott. He went from not serious to real serious. Even with all the questions that raises, investigators still can't make a case against David temple. So he goes on with his life, a free man. It's kind of hard to believe the woman that was once David temple's mistress is now a caring stepmom to his son Evan, even posting a photo of the two of them at a restaurant on her Facebook page. With Evan's mom gone, Heather is now raising him as her own. The years go on, but then in April of 2003, time catches up with David temple. Early in the investigation, detectives had delivered pieces of davidnd Belinda's clothing to the FBI in Washington, D.C., to be tested. Harris county investigators sent David and Belinda temple's clothing to the notoriously backlogged FBI crime lab. Since Harris county didn't have the necessary testing equipment. Then the 9/11 attacks delayed testing even more. Finally, detectives tell us they got results back. Tests on their clothes revealed gunshot residue on David temple's clothing. Which matches residue on the clothes the victim was wearing the day she died. Gunshot residue on the cheating husband's clothing the day the wife is shot dead? Forensics don't lie. This is a bombshell, and here's why. Up until now there has not been one shred of evidence placing David at the scene of the remember, he had what appeared to be an airtight alibi. Out shopping, caught on surveillance tape while the murder may have been committed. The gunshot residue can suddenly change the narrative. Friends and family don't know it, but this case is about to get another huge boost. Because across the country, another high-profile case is going on of yet another pregnant murdered wife. Laci Peterson, eight months pregnant, vanishing while her husband was gone for the day on a fishing trip. Belinda temple seemed to have all of the same elements that the Scott Peterson case did. But here's how this one may be different. David temple may be the only guy that gun residue doesn't stick to. I have moderate to severe plaque psoriasis. Now, there's skyrizi. Things are getting clearer, yeah I feel free to bare my skin
This transcript has been automatically generated and may not be 100% accurate.