Transcript for Mom of man convicted of murdering student in Brooklyn vows to win his freedom: Part 2
Reporter: Dorine Juliano is devastated. Her son is serving 25 years to life for a murder she says he had nothing to do with. She makes a vow to win his freedom by any means necessary. In 2006, she came up with this idea that she would investigate the jurors in the case. I was searching for the truth. I wanted to know why they came back with the guilty verdict. Why? She has a one-woman sting operation. A mutual friend of John's recognized one of the jurors. He said yeah, the guy with the balding head. He comes here to my house. The juror, juror number eight. Was Jason. Although he didn't know John juca personal, Jason aloe knew people who knew him. The key point here is less about how much did he know about these people and more did he intentionally lie to get on the I said okay, so I need to speak to this guy. And that's when I began my undercover work. I started to know his routine. He hung out on the corner. He was talking' about blondes. That's when I decided to go really blond. Dorine changes her hair color. She puts on spike high heels. She wears provocative clothes and changes her name to Dee Quinn. Reporter: Were you going to woo him. Yeah, I knew I needed to use whatever I could to get him to confess what happened. Reporter: One day, Dorine rides down Jason's block on her bike and strikes up a conversation with him and his friend. New to the neighborhood. I said I was from California, and eventually, I did turn around and started talking to Jason aloe, the juror on my son's case. Reporter: And so you struck up a friendship after that? I did. He needed somebody to vent to, and I was there. I was a very good listener. Reporter: And so you're talking to him the entire time with a recording device strapped to your body. Yes, yes. Reporter: And you kept it Between my boobs. He described my son as a tall, skinny kid with glasses and proceeded to tell me how he hated Jews. I'm prejudice. I hate Jews. And he said he hated Jews, believing John was jewish. I wanted to punch him in the face. I wanted to stab him. By law, you're not supposed to be. They read you a list of all the witnesses. If you know or affiliate with any of these people in any way you have to let them know. I was disgusted with him. Because he said it proudly. He committed very serious juror misconduct. And I've uncovered it. Depends on what he was asked in jury selection. It seems that he knew that he should have said more. In the context of jury selection. Did he lie? He says no. Dorine doesn't know what to do with the information, so she goes public and tells a reporter from "Vanity fair" all about it, and the result is a big feature article. Reporter: When you saw the pictures of your mom in "Vanity fair". Yeah. Reporter: Dressed up in the way that she dressed up. What was your reaction? It didn't even look like her. I didn't recognize her for a second, oh, my god! Tonight on "Nightline." Undercover mother. This has to be put down on the record. Was there anything that you felt that was odd or strange about this woman who suddenly becomes a friend of yours? She was coming on very strong, very strong. Do you ever recall saying anything like "I hate Jews." Can you tell me? I'm not a prejudice person. Is it anything you might have said in the past? What does that have to do with -- Just answer the question. Does it make sense? It does. I'm coming to a point. Don't answer. In one of the tape recordings, you say you hate Jews. That's your interpretation. Can you ever remember saying, I shouldn't have been in that jury? He doesn't remember saying that, mark. Do you, Jason, ever remember saying that? No. Did you commit perjury? Absolutely not. Do you remember anything about the people in that group during that process? No. Reporter: Meanwhile, Dorine goes back to court with the tapes. John juca's file a motion to get a new trial. On the grounds of juror misconduct. So the judge denies the motion for two reasons. The Jun judge was saying the juror didn't intentionally lie during the process. And secondly, the tape isn't necessarily reliable. He says there's no way to prove they weren't altered. He said that you were guilty of extraordinary misconduct. Did you go too far? Um, maybe it was misguided, but definitely not too far, because any mother would do it. Reporter: So now Dorine sets her sights on the star witness, John avee to. She hires a private investigator. Well, they wanted me to drive and interview him. Now it's many years later. Let's see who John is now. So they convinced him to meet in the car and had a tape recorder rolling. I just want the truth. The whole thing was a lie. The whole thing was a lie. He is now coming forward and saying that he made up the story. About juca's confession. And he was the most important witness in the case. Jace Al Peter got John avitto that he was in a mandated drug program, which should have put him into jail, but according to avitto, he had some sort of a deal with the prosecutors. And they helped me get out of those to keep me so I could testify. At this point, John, John juca's new attorney takes all this information to a judge in an attempt to get their case overturned. The judge's response to this is he grants them a new hearing. John avitto comes in. His first words were, apologizing to John. What was your reaction? It was like a weight was lifted off my shoulders. So the judge listens to all of this and decides that there was no deal. That John avitto's life was not helped by anything the prosecution did for him. Dorine still doesn't give up. And then she got an unexpected phone call from her lawyer. Reporter: In a stunning decision, a panel of four appellate judges overturn her son's conviction. The judges concluded that the prosecutor committed a clear violation of court rules. That they helped avitto. But John remains behind bars because the prosecution has appealed the ruling hoping to get the conviction reinstated. Meantime, Antonio Russo changed his story. What he said was he did it alone, that he shot and killed mark fisher. I want my name cleared. One of the worst things about this is people thinking I'm a murderer, and I want that wiped away, because it shouldn't be there in the first place. Reporter: Some people might argue that the fishers deserve closure in this as well. And they do, of course they do. Reporter: And you have empathy for them? Of course. Of course. But in the same respect, I've got to fight for my son's life. You know? I have to fight for my son.
This transcript has been automatically generated and may not be 100% accurate.