Transcript for Ex-wife of man convicted for son's hot-car death speaks out
Now we have this ABC news exclusive. Amy, you sat down with the mom of the -- that little boy left to die in the backseat of his father's hot car. An incredible story. The mom divorced her ex-husband because of all the information that came out yet she still thinks he's innocent. Innocent of the most serious crime, that is malice murder. Leanna Taylor wants nothing to do with her ex-husband and expresses anger towards him but doesn't think he deserves to spend the rest of his life behind bars. Leanna, this is your very first interview. Why are you speaking out now. It's been 2 1/2 years of very heartbreaking silence. You want to change the narrative. Exactly. That narrative up until now is the one a jury accepted that Leanna's ex-husband Ross intentionally left their 22-month-old son cooper to die in a hot car. There was no evidence in our relationship that suggested that he would harm anyone, much less his own con. We find the defendant guilty. Reporter: It was a hot June day, 92 degrees, Justin Ross Harris is supposed to drop his son cooper off at day care. Instead he drives to work and parks his car there leaving little cooper strapped into his rear-facing car seat. A 2-month-old child died in the back parking lot here. Reporter: Ross claims it's a terrible accident but as suspicion builds Leanna too comes under scrutiny. People looked at you and thought the worst. Uh-huh. Reporter: The public perception fueled by her own behavior in this infamous police video embracing her husband in an interrogation room. You were compassionate towards your husband which is something I think a lot of people look at and think how were you not upset? How were you not angry at him when you first saw him? It never crossed my mind that Ross had done it on purpose. Never. It -- it was an accident. But dent or not, he was responsible for the death of your son. How are you not angry? That didn't -- that wasn't sinking in. Since that day I have gone through all of those emotions. You've been angry at him. Yes. But that moment I went -- I hadn't accepted what had happened yet. Reporter: But what about this moment. Did you say too much? Why did you say that to him? I knew my husband. I knew his personality. Logically Ross doesn't shut up, so the only thing that I could think of logically what did you say to make them think that you did this on purpose. Reporter: But as police investigate they uncover evidence of dozens of affairs with women, men as well as text messages from that fateful day. Ross inside his office sexting other women complaining about marriage and fatherhood and on his computer, this video. I mean this kills. And it's a lousy way to die. Reporter: About the dangers of leaving pets in hot cars. Viewed by Ross just days before cooper died. Leanna divorces Ross but at his trial a bombshell. She takes the stand as the star witness for his defense. Did Ross love this little boy. Yes, he did. Very much. You went on the stand and supported your husband. Why did you do that? This is never about me defending Ross. When you get on the stand and you swear to tell the whole truth and nothing but the truth that's what you're supposed to do and that's what I did. I couldn't get up there and say that he was a bad father because it wasn't true. Was there ever any evidence presented at trial that made you question whether or not Ross was guilty of murder? Not guilty of intentionally murdering. Not, not planning the murder. No. What about Ross watching that video, that vet video of an animal in a hot car in the days prior to cooper's death? What do you make of that? We have a dog, many, many other people viewed that same video. Many, many people didn't then leave their son in a hot car. Right. Does he deserve to be punished in any way for what happened to cooper? I think that there has to be a level of -- a level of punishment. Has Ross ever apologized to you? Uh-huh. What did he apologize for? For not protecting our son that day. For not being faithful to me. For taking his family for granted. Do you accept his apology? I accept it. It's not going to change anything. What she does want to change is the people's perception of this case that only bad parents could leave their child in the car. She wants people to know it could happen to anyone so all of the things that came out about Ross in trial, she was afraid that clouds people's ability to conceive that they too could do the same thing and she wants to prevent this from happening again. Gripping to watch first of all but a little confusing because she thinks he should be punished but doesn't think he's guilty of murder. A lot of parents -- this happened 39 times just last year do face charges and are convicted on lesser charges, vehicular manslaughter or some sort of lesser charge. Negligence. Negligence, but malice murder. She doesn't think that it rises to that level. She doesn't think she planned -- he planned it. She doesn't think he intended to kill their son. She thinks he should have been responsible for being responsible for cooper's death. Seems like she had total faith in him. She wants to believe he isn't capable of something that horrific. Incredible interview, congratulations. You can see it on "20/20" at 10:00 eastern right here on ABC.
This transcript has been automatically generated and may not be 100% accurate.