he would talk about. reporter: even prosecution witnesses wound up vouching for ross as a good dad. a teacher from cooper s day care. he would just spend quality time with him interacting with him doing the activities. reporter: and some of those women who testified for the prosecution about sexting with ross? even they agreed he seemed to love his kid. what would he say about his son? that he was great, and that he loved his son. he just talked about how much he loved him and how he would never do anything to hurt him and that kind of thing. reporter: but the woman who should have known ross harris best was about to take the stand. she had something to say about the man who betrayed her, and left her son to die. and it may be the last thing you d expect to hear. coming up cooper was the sweetest little boy. heartache laid bare. cooper s mom tells her story. i just kind of went into a panic.
the case became a media sensation with more revelations. investigators said ross had done internet research on hot car death and even visited an online forum for people interested in living a child-free life. a monstrous portrait was emerging. but even after weighing all the allegations, ross s friends were still convinced he never meant to hurt cooper. did you ever hear ross get frustrated with cooper? no. reporter: treat him like he was a burden at times? no. reporter: because you know there are times when kids can get on our nerves. mm-hmm. no, no. there are times when you definitely need a break. okay? but he loved that boy. reporter: ross harris s family enlisted the help of defense attorney maddox kilgore and his team. the entire case was a house of cards. we felt that, despite public sentiment, and despite the
bravado of the state and the charges, we felt extremely confident that that house of cards was going to collapse in trial. reporter: in october, 2016, more than two years after the death of his son, ross harris went on trial for murder. death. deception. and a double life. reporter: chuck boring, the lead prosecutor, told the jury why ross s story had never added up. that chick-fil-a video showed cooper wide awake. that drive that was too short to forget a toddler. the car seat was just inches behind ross. and at ross s office, there was a photo of cooper and a gift from cooper. he even sent a text to leanna in the afternoon about cooper. when you getting my buddy, it said. none of that jogged his memory? there was just cue after cue after cue that if he had actually forgotten would have triggered something. reporter: and then the
the prosecution says the jury got it completely right. but hearing the word guilty was no cause for celebration. what i wanted to hear most is, you know, we can bring cooper back. you can t get that from it though. reporter: three weeks later, a judge sentenced ross harris to life in prison. sentence of the court is life to serve in confinement without parole. reporter: his defense team has already filed an appeal, arguing among other things that the judge never should have allowed all that testimony about sex into the murder trial. and the defense says inaccurate information released early on about ross s computer searches made it impossible for him to get a fair trial. our personal belief, not lawyer talk, our personal belief and knowing ross and knowing this case better than anybody in the world, ross harris is an innocent man. reporter: are you going to keep fighting? this case is far from over. reporter: having seen the
i will give it to you, if that s what you want. and i believe his answer back to me was, that s the last thing i want. reporter: prosecutors told us there was no evidence leanna knew what her husband was supposedly planning. and when they cross-examined her, they suggested she didn t know her husband at all. you d agree there s a whole part of his life that you had no clue about? i would agree that i did not know the depth. have you read the text messages that he sent to these other women? no. i have no i have no reason to have read them. okay. so if he s saying foul things to a 15-year-old girl, you wouldn t think that that was something different than the way he portrayed himself to you? i think it s horrible. reporter: the prosecutor pointed out that ross lied to her all the time. one example did you know that was the afternoon he actually called a prostitute and went to have sex with her instead of being at home with you and cooper?