The chief prosecutor in the murder trial of Oscar Pistorius today accused the Olympic athlete of "adapting" his story in an attempt to discredit physical evidence that the prosecution claims prove Pistorius’s version of events cannot be true. 

Under questioning from prosecutor Gerrie Nel over a series of police images depicting the bedroom where Pistorius slept with Reeva Steenkamp before he shot her to death on Feb. 14, 2013, Pistorius insisted that a number of key objects in the images must have been moved by police before they were captured.

According to Pistorius:

  • The bed’s duvet cover — shown on the ground in the photographs — was in fact still on the bed after the shooting.
  • The left side of the bedroom curtain — shown completely pulled aside in the images — was not fully opened.
  • An oscillating floor fan is shown placed “where it not possibly could have been.” 

When Nel asked why anyone, particularly investigators, would have moved the objects, Pistorius answered, “I am not a policeman.”

The location of the fan, in particular, is critical to the state's case. According to Nel, the photos show that the fan was blocking the door to the balcony. Pistorius has previously claimed he ran out on to the balcony to call for help after realizing he had shot Steenkamp, and that the fan was not blocking his route to the balcony. 

Nel argues that Pistorius never ran onto the balcony, and that both the door and curtains were open all evening. This is why, according to Nel, neighbours were able to hear screams. 

After meticulously going through the images and locations of the various objects, Nel said, "Mr. Pistorius, your version is so improbable that nobody would ever think it is reasonably possible."

"Keep trying, Mr. Pistorius. It's not working."

Nel also pointed out that Pistorius did not mention the discrepancies when showed the photographs on Wednesday. 

Pistorius shot Steenkamp, his girlfriend, through a closed toilet cubicle of his home. Pistorius claims he shot her by accident, mistaking her for a dangerous intruder. The prosecution says Pistorius intentionally killed her after an argument.

South Africa Pistorius Trial

State prosecutor Gerrie Nel became visibly frustrated while cross-examining Oscar Pistorius on Thursday. Nel focused on the Olympic athlete's flippant use of firearms and his apparent inability to remember details surrounding his firearm collection. (Marco Longari/The Associated Press)

When Nel pushed Pistorius on whether or not he truly believed he was firing his weapon at an intruder, Pistorius seemed to concede it was not necessary to discharge his weapon.

"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," said Nel. 

Pistorius responded, addressing the judge, that that was true. 

The exchange over the photographs came on a day when the prosecution consistently questioned Pistorius’s honesty, asserting that the double-amputee Olympian wouldn't "accept responsibility for anything" and arguing that the star athlete had a string of unlikely excuses why he wasn't to blame in the three gun charges he faces on top of murder for the shooting death of Steenkamp.

"Oscar Pistorius is not willing to concede anything. You are not willing to concede a single thing, are you?" Nel exclaimed.

The 'miracle' gun

Nel's remarks were sparked by Pistorius’s version of events surrounding a day on which he allegedly brought a loaded firearm onto a boat while friends wakeboarded. Nel pushed him to admit it was negligent of him — as a gun owner — to bring the firearm aboard for no obvious reason.

Nel also referred to a shooting incident at Tashas restaurant, in Johannesburg, in which a shot went off after a friend of the runner passed him a loaded gun under the table.

Pistorius, who faces a separate charge of firing a gun in a public place because of that episode as well as two other firearms charges, said he didn't have his finger on the trigger when the gun fired. This happened about a month before Pistorius killed Steenkamp.

The prosecutor noted that a police expert had testified that the gun could not be fired without pulling the trigger, and sarcastically described the discharge as a "miracle."

"We have you in possession of the gun, a shot went off, but you didn't discharge the gun," Nel said incredulously of the athlete's account.

“I’m putting it to you, you fired that gun. There is no other way,” Nel said. “You are lying.”

"I respect Mr. Nel's comment," Pistorius replied, "but I didn't pull the trigger on that firearm."

Pistorius also said two witnesses, a former girlfriend and a friend, were both lying about an incident in 2012 when the runner is alleged to have fired his gun out the sunroof of a moving car.

'Your life is just about you.'- Prosecutor Gerrie Nel to Oscar Pistorius during cross-examination

Pistorius insisted he wasn't guilty of a fourth charge against him, illegal possession of ammunition for rounds of .38-caliber ammunition found in a safe in his home after the death of Steenkamp. He said he was safekeeping the ammunition for his father.

But Nel said Pistorius' father Henke "refused" to make a statement to police on the ammunition being his.

Judge Thokozile Masipa will deliver a verdict because there is no jury system in South Africa. Pistorius faces 25 years to life in prison if convicted on a premeditated murder charge.

Accusations of ego

Early on during Thursday's cross-examination, Nel accused the Olympic sprinter of egotistical behaviour in his relationship with Steenkamp before he killed her, and described Pistorius's courtroom apology to his girlfriend's family earlier this week as an insincere "spectacle" that ignored the feelings of her relatives.

"Your life is just about you," Nel said.

Nel asserted that Pistorius was sometimes mean to Steenkamp, pressing him about her objection to him playing a song by American rapper Kendrick Lamar on a car stereo. Pistorius referred to the song in a cellular telephone message to Steenkamp that acknowledged her objections and has been included as evidence in the trial.

The prosecutor asked if the name of the song was "Bitch, Don't Kill My Vibe," but Pistorius said he couldn't remember the specific song. Nel responded that Steenkamp would have been right to take offence.

A phone message from Steenkamp to Pistorius that was shown in court includes the line: "You make me happy 90 per cent of the time and I think we are amazing together but I am not some other bitch you may know trying to kill your vibe."

Nel's tough questioning in the court in Pretoria was designed to counter earlier testimony in which Pistorius said he loved Steenkamp, a 29-year-old model, and was trying to protect her when he shot her without realizing, according to his account, that she was in the toilet cubicle.

Two contrasting images of the double-amputee runner have emerged in court: the defence-led image of Pistorius as a contrite man who had been worried about crime and made a terrible mistake on the night he killed Steenkamp, and the prosecution's depiction of him as an overbearing egotist who was obsessed with firearms.

Nel said he had checked all of Steenkamp's text messages on her cellular telephone and that the phrase "I love you" appeared only twice in those missives. On both occasions, he said, they were written by Steenkamp to her mother.

"Never to you, and you never to her," Nel said, addressing Pistorius.

"I never got the opportunity to tell Reeva that I loved her," Pistorius said in a soft voice. He did not look at Nel while replying to the prosecutor's questions, instead directing his gaze to Judge Masipa on the dais.

Pistorius's apology 'a spectacle,' Nel says

Nel also accused Pistorius of ignoring the concerns of Steenkamp's family by apologizing to them at the beginning of his testimony this week, rather than seeking to express his condolences in private. Steenkamp's mother, June, has attended court sessions this week.

"Why would you create a spectacle in court, in the public domain, in the public eye?" Nel asked. "Why did you put them through this?"

Pistorius said his lawyers had been in touch with representatives of Steenkamp's family, and that he had believed the family of his girlfriend was not ready to meet him.

"I completely understand where they're coming from," he said. "It's not that I haven't thought about them."

Timeline: Oscar Pistorius

With files from CBC News