Transcript for Oscar Pistorius Case: Murder or Mistake?
In recent years most of the stories written about Oscar -- centered around his drive to beat the fastest runners in the world despite being born with out functional Lex. Well now all anyone cares about is what drove this Olympian to -- girl for four times in the early hours of Valentine's Day. After being accused of premeditated murder -- stories released his side of the story for the first time today. And ABC's Bosnia -- Khatami has details. It's the mysterious Valentine's Day shooting that shocked. Paralympic mega star Oscar this story is accused of killing his age and cover model girlfriend at -- fifteen. With the way -- -- go acts and making it sits. -- importance and now this recently taped a reality show featuring the model. Added to the nation's heartbreak when it aired unseen footage on south African TV. I'll take climate -- so many amazing. Name me some things that adding yet that I didn't yeah. But today Oscar -- story as his calling her brutal death a tragic mistake. The track star appeared in court sobbing as his lawyer read Oscar's own account of what happened that night. They were both sleeping historians wrote when he woke up -- -- on the balcony and suddenly heard what he thought was an intruder in the bathroom. It fills me with horror and fear as I did not have my prosthetic legs on and felt extremely vulnerable. I knew I had to protect -- and myself in the pitch stark -- the double amputee says he grabbed his nine millimeter handgun. Rushed into the bathroom. And noticed an open window and got an intruder was hiding in the toilet room he fired shots through the locked door and yelled at -- to call police. There was no response that is what it dawned on me that it could have been -- who was in the toilet he then says he broke down the locked door to save his girlfriend. In all he shot at -- four times. And claims she died in his arms as he desperately tried to revive her I am absolutely mortified by the events. And the devastating loss my beloved to Riva. He's effectively admitting he shot an innocent person that puts it a tough spot legally. Gotta believe it is best hope is for a lesser charge rather than an all out not guilty -- Prosecutors say their evidence tells a different story they think the couple thought that night. And that steam -- fled into the bathroom to escape her enraged boyfriend believed prosecutors said today she locked the door for purpose. Will gets to that purpose victorious is currently losing the battle for public opinion in South Africa where incriminating claims are swirling in local media. New reports quoting police sources say. That steroids were found in his house and investigators are testing his blood for the drug that can cause road rage aggressive outbursts. If convicted of premeditated murder he's facing a sentence of life in prison. As the star athlete -- his case in court this morning -- listing comes remains were taken to a church in her hometown. Where family and friends gathered for memorial. Service this is based missing. -- side of the people that she knew it. -- can't be -- again. Re going to people opposed to things that we remember and -- -- my sister. And we hope. Trying to continue. -- the things that she trucks and expect to. Who missed the -- to dance -- family. -- -- -- -- -- -- -- -- -- -- -- -- But did -- one. Before the tragedy Oscar historians and -- -- -- -- we're South Africa's hottest new couple. -- modeling career was just taking off and Oscar noted the blade runner was a national hero. Making history as the first -- double amputee need to run in the Olympics. Kind of perceive muscles smoking several team. You -- to grow up yells to anything that any other kids and -- to. The world -- son Oscar as a charming and soft hearted fighter. But some who knew him say he had a short -- and was often paranoid about his safety. South Africa has one of the highest crime rates in the world. ESPN reporter Jeremy should have spent time with Oscar while filming a documentary. -- -- story is with someone like you like many people South Africa. Who -- to some degree in fear of being a victim of violence. Just a few months ago historians tweeted about possible reagans and how he would react. Nothing like getting home to hear the washing machine on and thinking it's an intruder to go into full combat recon -- into the pantry -- over the past few days corporate sponsors like Oakley and Nike have distanced themselves from the story is suspending ads featuring the track star at -- you refrain. And as a shocked nation comes to terms with this brutal tragedy. Perhaps -- comes only words are small comfort I'm -- -- -- Simon's. For Nightline I'm body cannot -- in South Africa.
This transcript has been automatically generated and may not be 100% accurate.