PRETORIA - In a pummelling cross-examination the prosecution called Oscar Pistorius's account of killing his girlfriend "impossible" and "a lie" on Thursday, highlighting apparent inconsistencies in key parts of his testimony.
"Your version is so improbable that nobody would ever think it's reasonably, possibly true it's so impossible," Prosecutor Gerrie Nel thundered during his second day interrogating the Olympian.
"Your version... is a lie," he insisted.
Nel also rubbished the athlete's claim that police moved important pieces of evidence after arriving at the scene early on Valentine's Day morning last year.
Under intense questioning, Pistorius said police moved fans, put the duvet on the floor and opened the curtains when they came to his villa, implying they had tampered with the crime scene.
"Is this one big conspiracy?" asked Nel with incredulity. "They would do all this to you?" Pistorius, known as the "Blade Runner" for his j-shaped prosthetic legs, has been charged with murdering his 29-year-old model girlfriend after shooting her four times through a locked toilet door.
He faces a life sentence if convicted.
The double-amputee, once revered for his triumph over disability, has said he fired the shots accidentally and did not mean to kill anyone.
He also testified that he feared someone was coming through the toilet door and that his life was in danger.
This seemingly contradictory account was probed at length by Nel, who drew a concession from Pistorius that the shots should not have been fired at all.
"We know for a fact there were no intruders in your house that night, we know for a fact there was no ladder against the wall," Nel said.
"We know for a fact that you had no reason to shoot, objectively speaking." Pistorius responded: "That's correct my lady." Pistorius's cross-examination is a key point in his trial and a stern test of both his version of events and of his resolve.
During the five-week trial the world-famous athlete has appeared fragile, frequently crying in court and becoming physically sick when gruesome details of Steenkamp's injuries were discussed.
Regardless of who Pistorius believed was behind the door, he could face a stiff sentence if Judge Thokozile Masipa believes he purposely used lethal force without reasonable cause.