Transcript for The Year's Shocking Trials and Tribulations
? ? Announcer: The year continues with Dan Abrams Reporter: It became the murder trial of the year. Bladerunner Oscar Pistorius, the first amputee runner to compete at an olympic games. Today was the first day of a very big trial, the legendary athlete accused of murdering his girlfriend. Reporter: Pistorius pled not guilty to the premeditated murder of girlfriend, reeva steenkamp. How do you plead? Not guilty, my lady. Reporter: But the prosecution was determined to prove Pistorius shot and killed steenkamp in a cold-blooded rage following a lovers' quarrel. I made a mistake. You killed reeva steenkamp. That's what you did. I made a mistake. What was your mistake? You killed her. You shot and killed her. Reporter: The story captivated the world. This is a guy who was competing in the able-bodied olympics as a guy with no legs, running. She wasn't breathing. There was a lot of crazy moments through the trial. Not to mention the fact that he was throwing up all the time. I guess, you know, you hear about athletes throwing up before a game. This was no game. Reporter: After seven grueling months, the judge finally rendered her verdict. The accused is found not guilty. Instead, he is found guilty of culpable homicide. Pistorius did not get first-degree murder because the judge loved him, and he is a superstar there, and he got kid glove treatment. Reporter: Pistorius has been sentenced to five years, but prosecutors have requested more prison time. If they win that appeal, he could face at least an additional ten years behind bars. Many other sports figures were caught up in controversy as well this year. But it was that infamous elevator surveillance tape released by TMZ sports, showing Baltimore ravens running back ray rice punching his then fiancee, now his wife, that caused the biggest firestorm. In the ray rice debacle, we have videotape -- not one, but two. First, we see him dragging his now-wife out of the elevator, obviously unconscious. But then we see the knockout punch from inside the elevator. Of course, the NFL said, "What? I didn't know about that." Well, why didn't they know? Reporter: The focus turned to exactly what NFL commissioner roger Goodell knew about that video when he suspended rice for only two games. They didn't want to know. They stuck their head in the sand and their butt, excuse me, in the air. This morning, the Baltimore ravens terminated his contract, and the NFL suspended him indefinitely. Reporter: Rice appealed his suspension and won. On November 27th, the NFL announced rice would be reinstated. It's still unclear where and when he will play again. I am not concerned whether I see him on TV on Sundays. I am concerned about domestic abuse, violence being unpunished. I think he should be in jail. So there. Put that in your pipe and smoke it. Another crushing blow for the NFL. Reporter: In September, Minnesota vikings' running back Adrian Peterson was indicted on a felony count of reckless or negligent injury to a child for beating his 4-year-old. When he did it, it came right on the heels of ray rice. Following his indictment, Peterson turned himself in to authorities and released a statement that same day. "I want everyone to understand how sorry I feel about the hurt that I have brought to my child. I am not a perfect parent, but I am, without a doubt, not a child abuser." He later reached a deal and avoided jail time after pleading no contest to a misdemeanor. It quickly sparked a debate on child abuse and corporal punishment. I do believe in spankings. More kids need to be spanked. That's how we were raised. Here is the deal. Anytime you leave bruises, that's not discipline -- that is abuse. He needs to be in jail. Reporter: Peterson's future in the NFL is still up in the air. A toddler left in the backseat of a car dies in the Georgia heat. Dozens of children died tragically this year after being locked inside cars in scorching temperatures. But the case of Justin Ross Harris stood out from the rest. His son died after being locked in a car for seven hours while Harris was at work. And other questions soon emerged about his behavior that day. He was having up to six different conversations with different women. Of what nature were they? The most common term would be sexting. It's tragic to lose a child. A lot of people are like, "That's punishment enough." Until they found out you were sexting, and then it's over. Reporter: The story seemed worse when detectives said Harris told them he'd done research on children dying in cars, because of fear it could happen to his own son. Shocking new details in the case of the father who's been charged with murder for leaving his -- Reporter: And when police in search warrants said Harris had spoken to family members before his son's death about how to collect on an insurance policy, Justin Ross Harris became the most despised parent in America. Harris insisted it was a tragic mistake, that he thought he'd dropped his son off at day care. He pled not guilty to eight felony counts, including malice murder. The trial is scheduled to begin January 12th, 2015. And what would another year be if we couldn't still talk about Jodi Arias? I think we secretly love Jodi Arias because we can't get rid of her. It's like she's guilty. She did it. And we're still having a trial. The simple answer is that he attacked me. Reporter: In 2013, a jury found Jodi Arias guilty of murdering ex-boyfriend Travis Alexander, but hung on whether she should face the death penalty. So this year, prosecutors tried her again to seek death. The entire defense team is back with Jodi Arias there. She's even got her chair screwed down like she had the last time, so she looks petite and frail and pitiful. Reporter: This time around, her attorney presented her not as the battered victim forced to kill in self-defense, but as a troubled, mentally ill young woman. I don't think there is any question that Jodi Arias is a sociopath. And people are fascinated by -- That's not a legal defense, Dan. Reporter: -- Watching her. But you tell me. You see, everybody as a sociopath. Reporter: No, Jodi Arias is a unique -- is a unique character. A unique sociopath. Statistically, when the state has another swing at the ball, a second bite of the apple, it works in their favor. But, I don't think they're going to give her the death penalty. Whether she deserves it or not is a different point. Reporter: If she does get the death penalty, Jodi Arias could become the first woman in Arizona's history to be executed.
This transcript has been automatically generated and may not be 100% accurate.