Nel derided the athlete’s repeated claims that he had shot dead his girlfriend by accident or “mistake”.
As Pistorius finally faced the State’s questions five weeks into his sensational murder trial, Nel accused him of tailoring his evidence, lying and failing to take responsibility for killing Reeva Steenkamp.
He began by saying: “Mr Pistorius you were and still are one of the most recognised faces in the world, agreed? You are a model for disabled and able-bodied sportsmen all over the world.”
Pistorius replied that he used to be until he made a “terrible mistake”.
At this, Nel demanded that he accept that he had killed Steenkamp, and displayed a close-up photograph of the bullet wounds in her head on screens in the High Court in Pretoria.
“You killed a person, you killed Reeva Steenkamp, that’s what you did… Say: ‘I shot and killed her’,” Nel said.
“Take responsibility for what you did. I know you don’t want to see this, but look at it!”
Pistorius sobbed in protest: “I remember… my fingers touched her head, I do not have to look at a picture.”
Judge Thokozile Masipa adjourned the court to allow Pistorius to compose himself, as she has done several times since he began testifying in his defence on Monday.
In the meanwhile, eNCA television had interrupted its broadcast of the trial due to the graphic content of the photograph.
When the session resumed, Nel asked Pistorius whether he knew what a “zombie stopper” was or had ever been in the presence of somebody who spoke about one.
When Pistorius said no, Nel prevailed over objections from the defence to introduce video footage showing him in the company of friends, shooting apart watermelons in target practice and remarking: “It’s a lot softer than brains but … it’s like a zombie stopper.”
Pistorius conceded that it was his voice in the video, and Nel drew a stark parallel between the target and Steenkamp, whom he shot repeatedly through a locked bathroom door on Valentine’s Day last year.
“You know the same happened to Reeva’s head, it exploded … It had the exact same effect, the bullet that went into her head.”
The State contends that the double amputee sprinter shot Steenkamp, a 29-year-old model, with intent after the couple had a row.
Pistorius maintains that he mistook her for an intruder hiding in his bathroom in the early hours of the morning, and acted in irrational fear when he fired four shots into the locked door.
Since taking the stand on Monday, he has under questioning from his defence lawyer set out a detailed account of the sequence of events that led up to the shooting.
He told the court he got up from bed to fetch an electric fan when he heard a noise and panicked, and only realised after discharging his firearm that Steenkamp was no longer in bed.
Nel grilled him about discrepancies between the statement submitted at his bail hearing and his testimony this week, notably that they differed on whether he stepped out onto his balcony, and picked apart Pistorius’s claim that the police had tampered with evidence.
He asked Pistorius to give him specific examples and the accused ventured that the fan had been moved by the police.
The prosecutor zoomed in on a photograph of extension lead where Pistorius claimed he had plugged it in, and asked Pistorius to agree with him that this would have been impossible because there was not a free socket left on it.
“My memory isn’t so good… I’m under a lot of strain. I’m defending my life,” Pistorius back-tracked.
Nel said he would prove that Pistorius was lying, and asked why he had taken care to say that he had “accidentally” fired the fatal shots.
“When I fired… I believed that someone was coming out of the toilet to attack me… I didn’t have time to think about what was happening… I believed that my life was in danger… Before thinking, out of fear, I had fired four shots.”
When Nel insisted, Pistorius conceded that he was concerned about the legal implications his answers would have.
“My life is on the line. Of course I’m thinking about the consequences of my answers.
Nel retorted: “And Reeva doesn’t have life anymore… Listen to the question and stop thinking about the implications for you.”
With the court about to adjourn for the day, Nel suggested that Pistorius was again welling up with emotion because he found himself being wrongfooted, and was called out of line by Masipa.
Pistorius, the first amputee to compete in the Olympics, faces life in jail if convicted of premeditated murder.