Nel: Pistorius's version of events a lie
The prosecutor indicated he was building a case to show the couple argued before the deadly shooting.
The Paralympic and Olympic athlete is accused of murdering Steenkamp at his luxury Silver Woods Country Estate home in Pretoria East on Valentine's Day last year.
The 27-year-old also faces gun-related charges in connection with two separate shooting incidents, one from a moving car and another at a crowded Johannesburg north restaurant.
Pistorius also faces a charge of illegal possession of ammunition.
The athlete pleaded not guilty to all charges on the first day of his murder trial on 3 March.
Pistorius survived a second day of relentless cross-examination from Nel, who is also known as the 'bull terrier'.
Nel focused on two general themes today, that Pistorius is an irresponsible gun owner and that he doesn't take responsibility for his actions.
As part of a clear strategy, the state jumped from one topic to the next when questioning the athlete.
He moved from the Whatsapp messages sent between Pistorius and Steenkamp to the gun-related charges and then back to the 14 February 2013 shooting.
The athlete claimed police tampered with the crime scene, his friends lied and his defence team gave him poor legal advice.
Nel spent the afternoon focusing on a fan in the doorway being in the way of Pistorius shouting for help from the balcony and the curtains being wide open and not closed as stated.
He said the evidence showed another story.
"Your version is so improbable that nobody would ever think that it is reasonably, possibly true."
Nel told the court that there was no significant evidence pointing to the accused telling the truth.
"We cannot lead eyewitness evidence because the one witness we would want to call is dead."
Nel wanted Pistorius to explain why police officers would've tampered with the crime scene.
He said that would involve the police opening his bedroom curtains, moving the fan and throwing the duvet onto the floor before taking the first round of crime scene photographs.
"Is this one big conspiracy? Why is it that they would do all this to you?"
Nel also accused Pistorius of refusing to take responsibility for the three gun-related charges he's facing.
The bigger accusation is that he's not willing to account for what happened on Valentine's Day last year.
"It's the strangest day today. You just don't take responsibility for anything, you just don't do anything wrong. Any gun owner would say it's wrong, why can't you do that?"
Nel also returned to the messages between the couple and the crucial aspect of intent relating to the shooting.
No matter which way Nel phrased his questions, there was no straight answer from Pistorius.
He again asked if the athlete fired four shots accidentally.
Pistorius admitted he had no reason to shoot, but said he did so out of fear when he heard a noise in the toilet cubicle thinking intruders were about to attack him.
The prosecutor asked the athlete, "Did you want to shoot the people coming out of the door or not?"
Pistorius responded, "I didn't have time to think about if I wanted to or didn't want to my lady. I heard a noise coming from inside the toilet and I discharged the firearm."
The athlete became emotional, reiterating how he felt.
"I didn't intend to shoot. My firearm was pointed at the door because that's where I believed that somebody was. When I heard a noise, I didn't have time to think and I fired my weapon. It was an accident."
Pistorius said he could not remember how many shots he fired through the door and was only told later that it was four times.
Nel then quickly questioned whether his evidence about the shots was drawn from his memory or a reconstruction.
He said it was based on facts he had obtained after the shooting.
Nel is almost certain to explore this line of questioning again.
NEL MAINTAINS COUPLE HAD ARGUMENT
The prosecutor also indicated he's building a case to show the couple had an argument shortly before Steenkamp was killed.
He said he'll show circumstantial evidence that Steenkamp ran to the bathroom screaming before the four shots were fired.
Advocate Barry Roux intervened, saying he cannot prove this.
Turning his attention to Steenkamp's last meal, Pistorius said they had supper at about 8pm.
Nel asked Pistorius whether it was possible his girlfriend could have eaten after that.
"Is it possible that she got up later and went down to eat something without you knowing?"
Pistorius replied, "I don't think so my lady."
NEL SLAMS APOLOGY
Pistorius's apology to Steenkamp's family earlier this week also reemerged in court today.
Nel slammed the apology as just another example of his self-centred personality.
He said the words "I'm sorry, I killed her" are not in his apology.
"You are sorry you have to think of them, you are sorry for their pain and sorrow, but you're not sorry that you killed their daughter."
He said Pistorius chose to make a spectacle in court in front of the world.
Nel said if the athlete had to apologise in person, he'd have to take responsibility for his actions.