Transcript for Oscar Pistorius Explains His Side of the Story
But first the trial of Oscar Pistorius ready to make headlines again. The olympic runner expected to take the stand this week. He will tell his side of the story, murder is never on his mind, and killing reeva steenkamp is, he is going to say, a tragic mistake. Ryan smith is with us. Reporter: Good morning, in South Africa when a defendant takes the stand, he goes first. Not so here in the anything but Normal Oscar Pistorius trial trial, and it could work to his advantage. Oscar Pistorius back in court after a ten-day layoff. But he won't be telling his side of theory just yet. You always want the confident testifying at the end rather than at the beginning. Reporter: The defendant's case, sprinting out of the Gates with a pathologist. He's expected to refute their theories about her position when he blasted four shots through a locked bathroom. Killing her in the early hours of Valentine's day last year. She was standing in front of the door, facing the door. Reporter: Mihe said he mistook her for an intruder. But the witnesses said he intentionally killed her, the neighbors saying they heard screams. Jarring autopsy photoing of her body, causing the track star to break down repeatedly. And prosecutors depicting him as a gun-toting loose cannon. This is a picture of an armed Oscar Pistorius. And uses text messages to show the relationship between the pair. I'm scared of you sometimes. What will he say in the court? Prior to trial, he provided an of paper that gave clues. I fired shots at the toilet door and outed to reeva. Reeva was not responding. It dawned on me it could have been her on the toilet. So dispute the was anything but loving. She was not standing, and by far the most important, to get the jury to believe every bit of his account of what happened that night. We will be covering the trial all week on "Gma." And once again, over to Ron.
This transcript has been automatically generated and may not be 100% accurate.