Transcript for Woman's Pastor Love Ended in Murder
Reporter: A small church in the heart of the bible belt. Its pastor, a suave, smooth talking reverend david love, best friend of the now murdered insurance salesman randy stone. Police are curious why both love and stone's widow teresa seemed to go out of their way to establish an alibi -- so I left dress barn around 2:41. Reporter: Police are starting to suspect that pastor love may have been living up to that suggestive name. There are rumors of an affair between the pastor and teresa. And they're making the case that the affair was the motive for murder. We have a page and a half of things that's not jiving. This was a planned killing. No. It was a planned premeditated killing and more than one person was involved. I have told you everything that happened on that day. Well I'm telling you that they have -- I have receipts to show you. My daughter was with me. I already know what you're going to say, but I have to hear it from you. Yes, we had sex and you know that. I know that and you know what? I am not going to judge you for that. Initially she denied ever having been unfaithful to her husband, then she admitted to sexual affairs. Then to a ten-year long affair, where they're having sex daily, with the pastor of her church. Reporter: But their clandestine affair becomes harder to hide, when teresa ends up pregnant. And the big problem with that? She's married to a man who had a vasectomy! Randy had had a vasectomy, previously, so, came as a real shock. Reporter: Were you suspicious? Randy and, and teresa just presented that it's only, maybe 99.9% effective, and that was the one little sliver of a chance that, that they had, and it happened, so it, it was what god wanted. Reporter: Divine intervention? Not even this man of faith was fully buying that. Randy matches "mother theresa's" betrayal with one of his own. He secretly takes her off his life insurance policy and makes his children sole beneficiaries -- to the tune of $600,000. She was not the beneficiary, and so I had to call her and inform her of that as well. Reporter: What was the conversation like? Total shock, that he could've changed that without her knowing that that was the case. Reporter: Randy's suspicions were spot on. That baby was the love child of his good friend and spiritual counselor, pastor love. Was there ever a time that you became pregnant with david's child? Yeah. That was a long time ago, wasn't it? Yeah, it was about six years ago, actually. What happened to the baby? I miscarried. Okay. Reporter: Turns out, someone else was suspicious of theresa and her pastor -- the pastor's wife kim, who tells police her husband was spending a little too much time puttering around the garage. He went to the garage to get his shoes because he said his feet were cold and I said that -- "what are you doing out here?" And he said, "i am putting my shoes on." And I said, "you are hiding something from me." Reporter: Kim love, doing a little bit of her own investigating, also discovers a hidden cell phone in the garage. I knew it was from teresa because I saw the texts from her. Reporter: But was the affair alone enough to turn pastor love into a killer? Police soon learn that there was also a rift between david love and randy stone over church finances. About two weeks before the murder, randy stone announced to pastor love that he was leaving the church. Money was disappearing, and randy didn't think that was right. Randy stone was a threat to david love for two reasons. He was about ready to -- you know, take -- take away teresa and randy stone also knew enough that could've crashed davis love's career. Reporter: So police had a motive. All they needed now was the evidence. Police start to turn the screws on teresa. Sometimes the smallest of details becomes the biggest of bombshells -- and detective rosewarren zeroes in on small discrepancy in teresa's story. Remember, after finding the body, she told her parents that randy had been shot, but she omitted that little nugget when she called 911. Who told you that he'd been shot? How did you know that he'd been shot? And why didn't you tell us? You're not being truthful with me, teresa. I, I didn't know. You're not being truthful. I didn't. He sent me a text and told me. Who did? Say it. Brother love. Reporter: There it is. Teresa finally gives him up. Her cohort, her lover, the man who pulled the trigger. Brother love. I think she just said, "you know what, I'm done. I'm done, I'm not going to continue to protect him, I'm going to throw him under the bus, and I'm going to save myself." Reporter: But teresa is going to betray her beau again! Only minutes later, teresa, still playing the role of a grief-stricken widow, tries to get brother love to confess to murder on a taped phone call. Pastor, this is theresa. Hi. We need to talk, okay? Now? Yes, now. I want to know why. Theresa, what? You know what. I need to know why. I need to know why you killed my husband. I need to know. Reporter: But alas, there would be no come-to-jesus moment from pastor david love. He doesn't take the bait. So police decide to bring him in for in person questioning hoping they can break him in the interrogation room. I definitely need some kind of representation because I am a preacher. I don't know the law. Reporter: But while pastor love wasn't talking, teresa was spilling it all. Did he say how it happened? He said he walked into the office and he aimed and didn't even look. So he said he pulled the trigger? That is what he told me. Reporter: Eight months after the murder of randy stone, police finally take pastor david love into custody. A shocked community comes to grips with a sacred trust broken. David love betrayed his church. He betrayed his faith. He betrayed everything he felt dear, to pursue this woman. Reporter: In november 2011, pastor love takes plea deal of second degree murder. He's serving life in prison and can eligible for parole in 2036. Teresa, indicted for conspiracy to commit murder, took a plea deal to have charges reduced and as part of that deal had to acknowledge her role in the crime. She admitted that she gave david the alarm code to her house and the combination to randy's gun safe so that he would be able to go into her home when nobody was there and get one of the guns. Reporter: Teresa was sentenced to 8 years in prison. In, in my mind I feel like she is every bit as guilty as, as the pastor, the only difference is he pulled the trigger and she didn't. Reporter: And as for david love -- the pastor who eulogized the man he murdered? David broke all the ten commandments, every one of them. He obviously lied. He committed murder, he committed adultery, he committed, you know, false witness. I mean, you go on and on, david committed, david broke all ten commandments. And so that is the ultimate act of betrayal. Have you ever been betrayed by someone you trusted tell us on twitter use the #abc 2020, elizabeth and I will be right
This transcript has been automatically generated and may not be 100% accurate.