The Olympian is claiming "putative self-defense," lawyers who are knowledgeable about the case but are not representing Pistorius said. The lawyers, drawing from the unusually detailed affidavit Pistorius' presented in his bail hearing, said Pistorius will maintain that in a darkened room in the pre-dawn hours of Feb. 14, and in a calculation that was gravely mistaken, he decided to fire the shots that killed the 29-year-old model and law graduate because he was certain she was an intruder and both their lives were in danger.
It's a difficult defense for any accused, legal experts say.
"The fact that he has admitted that he has killed her by pulling the trigger means the state has a prima facie case and it is expected of the accused to come and convince the court otherwise," Marius du Toit, a former prosecutor, magistrate and now defense attorney with over 20 years' experience in South Africa's justice system said. "His version is going to be exposed and scrutinized in the finest, finest detail."
While the news-dominating nature of Pistorius' case echoes that of former NFL superstar O.J. Simpson, experts point out the crucially different legal implication. Simpson denied any involvement in the killings of Nicole Brown Simpson and Ronald Goldman, for which he was acquitted, leaving the prosecution to prove its case.
Even with the principle of innocent until proven guilty, for any defendant in Pistorius' circumstances, "it's on you to come and show to the court that what (you) did was not so unreasonable," Du Toit said.
If the Paralympic champion is to be acquitted of murder - and also culpable homicide or negligent killing, which carries a mandatory five-year prison sentence in South Africa when a firearm is used - a judge must find Pistorius had no intention to kill Steenkamp and believed he was following the law to protect himself and others. The judge also must find that any other reasonable person in his situation would have done the same.
Putative self-defense is "extremely difficult" to show, said leading firearm lawyer Martin Hood, predicting an "uphill battle" for Pistorius at trial.
"I do not see how Oscar Pistorius could have concluded that a closed door constitutes danger to such an extent that his life is in danger, bearing in mind that he had gone into that situation," Hood said. "So, it begs the question why did he go looking for trouble?"
Why didn't he check where Steenkamp was, or just leave the room and the perceived danger? Simply, "what he should have done is ... got out the bedroom," Hood said.
There are clues to Pistorius' planned defense in his affidavit. References to his fear of South Africa's high rate of violent crime. "A sense of terror" rushing over him, he testified to in the document, when he realized someone was in the bathroom. Pistorius says he shouted for any intruders to get out of his house and for Steenkamp to call the police before he shot. Actions, his defense may argue, of a reasonable man who believed he was following the law.
"(We) Believe that Oscar's account of what happened on that terrible night in February will be borne out by the evidence that the defense team will lead in court," his family said Sunday.
But records from cellphones found in the bloodied bathroom will be scoured and neighbors will be questioned over a loud argument between Pistorius and Steenkamp that the prosecution says took place that night for indications of a possible motive.
The case also will be closely scrutinized by legal commentators, who say almost unanimously that South Africa's often criticized criminal process will be on trial alongside the country's one-time sporting hero.
Already stung by former lead detective Hilton Botha's bungled testimony in Pistorius' bail hearing, and Botha's admission to amateurish errors in the initial stages of the investigation, South African police declined to comment on details of the investigation. Brig. Phuti Setati, a senior police spokesman, only said the evidence-gathering was ongoing and the investigation was "progressing very very well."
Pistorius' character and his actions around guns could become circumstantial evidence, Hood said, with unconfirmed reports of moments of aggression and a careless attitude with firearms.
Yet, the prosecution's decision to press a premeditated murder charge, because they say Pistorius took the time to put on his prosthetic legs before the shooting, is flawed, Du Toit said.
"I honestly felt there wasn't any justification for (a) premeditated murder (charge)," Du Toit said, "unless something came out in their forensics that we don't know of. And we won't know until trial."
Pistorius says that he did not have his prosthetic legs on and was walking only on his stumps and felt "vulnerable," the most stark and possibly pivotal difference in the prosecution and defense versions and where forensics relating to the height or angle of the bullet holes in perhaps the most crucial piece of evidence - the toilet door - could be definitive.
It all could paint a picture of Oscar Pistorius as a cold-blooded killer, furious and intent on murder following an argument, as the prosecution alleges, who took the time to put on his prosthetic legs before striding to the bathroom and killing his cowering girlfriend.
Or as a terrified disabled man, standing on the stumps of his amputated legs and shooting to protect himself and the woman he loved from what he thought was a dangerous criminal.
The trial is likely to swing between these vastly different preconceptions of Pistorius.
- AP