Transcript for Woman Becomes Star Witness at Own Murder Trial
"20/20" continues with the burning bed. Once again, Jim Avila. Reporter: In the modern tower that is Charlotte's mecklenburg county courthouse, the state of North Carolina is working overtime to put Mike mead to death for the murder of his pregnant fiance, Lucy Johnson. Did you kill Lucy? Absolutely not. Absolutely not. Not one thing to do with Lucy's death. Reporter: Did Mike mead murder Lucy Johnson? No, he didn't. Reporter: And how do you know that? All the evidence says that he didn't. Reporter: Really? What about all those women prosecutors say Mike mistreated. Many of them at the end of the relationship were quite unhappy with you, right? They were angry at you. Sure. I wouldn't doubt that. They said at my bond hearing that there was eighteen women that came forward and signed sworn affidavits of abuse, that I'm a violent person, and I challenge you to show one. Not one. There's never been one complaint from any woman that I've ever been with that I've laid a hand on them physically. And are there girls out there that ended badly with? Who hasn't? Reporter: But you never hit any of them? Never. Reporter: Never threatened them? Never. Never stalked any of them, never burned any of their houses. Never raped anybody, nothing. The expectation coming from the d.a.'s office is that we're going to hear a lot of these women. Reporter: But the jury never hears that. We don't see not one of these women take the stand. Reporter: That's right. The judge ruled that their stories were inadmissible, irrelevant because none of those women had ever accused him of a crime. Okay, but what about the engagement ring, the so-called blood diamond? Prosecutors say its part of the motive. Mead was done with Lucy, didn't want that baby and wanted his ring back. It's a $15,000 ring, just never was found. We thought -- we found that to be very, very strange. Very odd. Reporter: But it's not airtight, because it wasn't like it was found in Mike mead's pocket nor his drawer or in his car. Right. Reporter: It just wasn't found. It just wasn't found. Reporter: Mike mead lives alone, so, on the night of the murder, there's no one but his dog to vouch for him. And when I went to bed that night, god knows I didn't think I needed an alibi. You know, if the dog had talked we'd be in good shape but you know, dogs can't talk. Reporter: But mead offers police three electronic alibis. First -- he says his alarm system, as he demonstrated to us, shows he was at home all night. Two -- his cell phone also puts him at home all night. Three -- he was playing madden NFL on playstation and the timestamp on the game places him at home at the crucial time. But how does mead answer the prosecution claim that the DNA evidence proves he forced sex with Lucy on the night of the murder and lied about it? Mead's defense investigator Steve Ehlers admits if the DNA found in Lucy was fresh, Mike was there that night and murdered her. The perpetrator goes in, rapes her, shoots her, burns her house down. Reporter: But on cross examination, the prosecution witness is forced to concede that critical DNA may not be all that fresh and just as Mike claimed, could have been from sex days before the murder. That semen was not the home run or the smoking gun they thought they were going to have. Reporter: And if that isn't enough of a Perry mason moment, listen up. The defense is granted a rare gift. The judge allows them to stand up in open court, in front of the jury, and not only proclaim Mike mead's innocence, they get to point their finger at the man they say is the real killer. In North Carolina, the rule is pretty strict, you can't do that. Unless you have got direct evidence pointing to the guilt of someone else -- relevant evidence. Reporter: Unleashed, the defense turns prosecution and puts Jim spelock on trial. Starting with his alibi, that he was at his house with his baby, his roommate didn't hear him leave, and there was a woman who first told police spelock and she were texting all night. But then revised her story. Did I think it was weird that he sent me a text at 3:00, yes. Okay. It was out of character for him. She showed back up at the police department and said, he didn't text me all night. Actually, he stopped texting me for two and a half hours. Ironically, at the two and a half hours when Lucy was being killed and her house was being set on fire. Reporter: In fact, by the time of the trial, Lucy has beende ad for three years. But now the jury is about to hear from her again. That's right. Lucy becomes the star witness at her own murder trial. Offering stunning testimony from the grave. Written in this pink polka dot notebook. A journal Lucy kept to build a custody case against Jim spelock Lucy told us over and over again in her own words who she thought she was in danger from. Reporter: And it wasn't just all about that pink notebook. The prosecution witness, Deana Bradshaw, reluctantly delivered some devastating evidence in Mike mead's favor. And she said, "Well, if anything happens to me, you know who did it." And so she was referring to Jim spelock. But it was all in laughter. Reporter: Laughed it off, maybe. But then she brought it up again. But she had said, "Well, remember what I said," you know, referring to if she's killed, that Jim spelock did it. And we were laughing and she left. That was the night she was murdered. Reporter: And in that pink notebook, Lucy also documents accounts of spelock's online gambling and an interest in cross-dressing that extended to buying sexual paraphernalia on the internet while he was supposed to be working at the nuclear power plant. Just about two weeks before her death, for the first time ever, she was able to document, to actually document on the computer, that he was purchasing these items. Reporter: Documentation Lucy had just turned over to her custody lawyer days before her death. Mr. Spelock was aware that she had the proof of her allegations. Reporter: That's the defense case. Jim spelock murdered Lucy Johnson because she was about to win the custody case and reveal his darkest secrets. How more definitive can you be? That's another reason why at first we felt like it was him. But I've learned -- don't jump to conclusions. He was perfect person to be framed for a crime. Reporter: Jim spelock turned down our requests for an interview, but denies he murdered Lucy or bought women's clothes for himself. And prosecutor Eddie Meeks believed him. Regardless of all these different arrows pointing, all these red herrings, at the end of the dashy, when you weigh all the evidence, it was only one arrow and it pointed at Michael mead. Reporter: But who does the jury believe? What would you make of those writings in Lucy's journal, enough to influence how you'd vote on the jury? Let us know on Twitter, use #abc2020. You'll hear from that jury when
This transcript has been automatically generated and may not be 100% accurate.