Transcript for Woman who spent 23 years in prison for murder on her life today outside a cell
??? free, free, free Tyra ??? Reporter: This is a moment Tyra Patterson has dreamed of. Finally embracing these teens who she says helped save her life in a campaign for her freedom. Tyra wasn't much older than them when she was imprisoned for murder. You remember me, huh? Yes. Reporter: Even though she didn't pull the trigger, didn't even have a gun. Her confession coerced, she says, raising questions about the issue of mass incarceration. Leading to a campaign to set her free. Celebrities even joining the cause. And I am Tyra Patterson. Reporter: Then a stunning turn. The victim's sister coming to Tyra's defense. Do you think Tyra Patterson is in any way responsible for your sister's death? No, I don't. Not one bit. Reporter: For Tyra the nightmare began 23 years ago, when she and her friend Becky are hanging out smoking pot in 19-year-old Tyra's apartment in Dayton, Ohio. They head out to look for a set of missing car keys and meet one a few acquaintances and wind up in an alleyway. Sitting in a car, 18-year-old holly Lai, her 15-year-old sister Michelle, and three other friends. I had a really bad feeling, a knot in my stomach that told me something was going to happen. Reporter: They were approached by a rowdy group. Among them Tyra and 22-year-old la shoouna Keeney who has a gun. Holly Lai called out for me, she said please make them stop, please tell them we don't have anything. What did you say to them? I walked up to Lashawna Keeney and was like why don't you chill out. And that's when she brandished the gun. Reporter: Tyra heads back home but back at the car the situation is escalating. There was a girl at my sister's door trying guite necklace off my sister and couldn't do it. That's when she took the gun across me. And I turned and she shot her right in front of me. We heard a gunshot. We actually thought they were shooting at us. Reporter: Holly's sister Michelle shot dead right in front of her eyes. I remember falling to the ground going why? Please somebody help us. And I start running door to door to door just pounding on doors, someone call 911. We got doors shut in our face. No one would listen. Reporter: What she doesn't know at the time is that Tyra did call 911. Please hurry up and come I think they got robbed. It was some girls in a car. It was? Girls in a car? Yes. Your name please? I was very scared. She said what is your name? I lied and said my name is tiara. Why did you do that? I knew someone had got hurt and I didn't want to be part ever it. Reporter: The next day Tyra is brought in for questioning. In the investigations office sitting with Tyra -- Tyra Lashaun Patterson. Tell if you would the event that took place this morning. Reporter: She tells the detective that she stole a necklace off the victim. I seen a girl in the back and she had a necklace on. I took the necklace. Reporter: Tyra says under pressure of the investigation she falsely confessed. What are you thinking at that moment? Because you look like a deer in the headlights. I though the was about to save my life. And when we were done I said am I about to go home? He said no, you're going to be books for murder. She's among five people arrested. Four would be charged with aggravated robbery anding avaitded murder. When someone's killed during the commission of certain crimes, in this case robbery, those committing the crime can be held responsible. So you're being charged with murder and robbery and sent to jail. What were those hours like, Tyra? They were long. Scary. Reporter: When Tyra goes on trial the next year, she says her lawyers advise her against testifying. But that confession tape is played. 18:42 hours. Reporter: Montgomery county prosecutor Leon dedonne says the tape was key in proving Tyra's guilt. It's a powerful piece of evidence that shows not only is she guilty in this but also it's not a coerced statement. The tone is calm. They're sitting next to each other. They're talking. He makes it clear that Tyra Patterson is no victim in this case. The victims in those case were those five girls in the car with the other gang of five people including Tyra patson attacked them. Reporter: At 20 years old Tyra found guilty, sentenced to 43 years to life in prison. As for Keeney the trigger woman she would take a plea deal. 30 years to life. I look at the jury and I said I didn't do anything. From themost moment she went behind bars Tyra vowed to fight her conviction. A middle school dropout, she uses the confinement to improve herself, learning to read, earning her G.E.D., even becoming a pair alegal. The only way I could fight was toejt myself. Reporter: And remarkably she becomes a mentor, reaching out to tell her story to high school students. Stay in school. Reporter: And then after 17 years in prison she meets David singleton of the Ohio justice and policy center. We got transcripts. Reporter: Tyra tells David she made a false confession. That necklace she was convicted of stealing, she picked it up off the ground. I couldn't believe the level of representation she got was sko bad. Reporter: In an affidavit Tyra's public defender said he was disappointed when she was convicted and that "At the time we did not have the means, resources or expertise to help the jury understand that Tyra's confession was false." What was the biggest omission as far as you're concerned? The 911 call should have been put before the jury, period. Reporter: Incredibly, that 911 call placed by Tyra was never played in court. Patterson's trial lawyers say they didn't introduce the call because they felt it was incriminating that she gave a false name. But it's evidence some jurors say that would have swayed their votes. Looking back now, I know she is not guilty. I'm just so sorry that it happened to her. No, not guilty. Not guilty. It bothers me some now. It sure does. To take that away from an individual, that much of their life, over half of her life. Reporter: David creates a social media movement. With politicians and celebrities joining the effort to free a woman they feel was wrongfully convicted. And I am Tyra Patterson. Reporter: Then holly Lai, who saw her sister shot right beside her, hears of those revelations and writes a letter to governor Kasich. I feel bad that Tyra has been in prison for so long for crimes I now believe she did not commit. Reporter: But it came at a price. I no longer speak with any family member on my dad's side or my mother's side. They all disowned me. No matter what they said, I was not going to let her sit in that prison. Reporter: Holly's sacrifice likely the game changer. My baby! Reporter: After 23 years Tyra Patterson was finally granted parole. I felt vindicated. Reporter: Now at 42 years old she's starting over, trying to regain those lost years with family. Did you think this moment was going to happen? I would lie to her and say I have faith, but it was diminishing. Reporter: She's now working as a paralegal for the same organization that helped get her out of prison and has her own apartment in Cincinnati. Is it jarring being in a cell for so long and now you've got in kind of space? Being in a 10 by 12 I think it is cell for 23 years. With a roommate. The best advice I can give you all is to stay in school. Reporter: Tyra continues to use her story as a cautionary tale for others. Surround yourself with people who will challenge you. Reporter: Sharing her story at schools and colleges across the nation. No drugs or alcohol. I'm living proof it does not work. My main message is to tell them to stay in school, graduate and reach your goals. Reporter: She's even stayed in touch with that group of high school students who she says gave her hope during the dark days of prison. Now y'all got me crying. When you started to Skype with her, when you actually saw her, this is a woman who's in prison. Was that weird? It wasn't weird. But it was just amazing to see how she could contain and still have happiness in her life. Reporter: What have you wanted to say to her? I just want to say thank you to everything. Reporter: You want to say thank you to her. Even though you helped her. Yes. I think she helped us more. Reporter: She's been out of prison now a couple of months. Yes. Reporter: So we thought it's probably about time that you meet Tyra. Okay? Oh, my god. I'm so happy right now. Hi, girls. Ore, my goodness. So you call these folks your kids, huh? Yeah. They're my babies. Thank you. Thank you. Thank you. Do you all remember everything we talked about? Yes. Stay in school. And don't do what? Drugs. That's right. I believe in my heart that if it wasn't for holly Lai and my babies that our voices would have been a little down. So thank you. Reporter: Soon more students anxious to meet the woman they worked so diligently to help free. Hi. Reporter: Emotions spilling out on both sides. You remember me, huh? Yes. Reporter: Then a special chant. ??? Free, free Tyra ??? ??? free, free, free Tyra ??? ??? free, free Tyra ??? ??? free, free, free Tyra ??? what's next? A pardon. God willing, a pardon. It's not an option for me. It has never been an option for me. Ever since I became conscious.
This transcript has been automatically generated and may not be 100% accurate.