13:01 GMT - Closing - We are now closing this Live Report on Oscar Pistorius's evidence to his murder trial for the day.
Keep following AFP's coverage of this compelling case as it continues, with a scheduled finish on May 16.
12:54 GMT - Pressure mounts - Nel was piling the pressure on Pistorius in the moments before the adjournment was granted.
AFP's Stephanie Findlay in court said the athlete looked like he was "crumbling".
"You're building a version that is so improbable no one would ever believe you," Nel says.
"I understand it doesn't sound rational, but I wasn't in a rational frame of mind," Pistorius responds.
Nel is set to pick up tomorrow with a different section of questions, which is why the early adjournment was granted today.
12:53 GMT - COURT ADJOURNS FOR THE DAY
12:51 GMT - Prosthetic legs - Pistorius describes trying to put his prosthetic legs on "as quick as I could" in the aftermath.
"Put on my prosthetic legs, ran back to the toilet... I tried to shoulder-charge the door, nothing happened," he adds.
Nel is consistently deeply sceptical of Pistorius's version of events.
12:44 GMT - Emotional - "Why are you getting emotional now? Is it about what happened or is it about the questions?" Nel demands.
"It's emotional memories for me," Pistorius says, his voice trembling.
12:39 GMT - Ladder - Nel asks why, if Pistorius had thought intruders had entered his apartment by climbing a ladder, he didn't check for one.
Summarizing Pistorius's evidence, Nel says: "'At this stage, I don't know, I was still fearful of intruders' but if that is even remotely true... I don't understand why you didn't check for a ladder."
Pistorius dismisses this point.
He then says he checked the balcony but tries to row back from this, prompting fierce questioning from Nel, who again accuses him of tailoring his evidence.
"If you checked the balcony, there was at least doubt in your mind that Reeva was on the toilet," Nel says.
12:33 GMT - Checking for Reeva - Nel asks Pistorius why he didn't check for Steenkamp on the floor.
"There's one very important aspect you forgot to mention -- why would you not check the bedroom door?" says Nel. "Why would you not check that she left through the bathroom door?"
"I feared now that I had shot Reeva," says Pistorius.
"If Reeva is not in the room behind the curtains, the next place one would look is if she left through the door," says Nel.
"Why would you think it's Reeva in the bathroom if you haven't checked everywhere?"
12:26 GMT - Tears - Nel asks Pistorius what happened immediately after the shots were fired.
Pistorius says he screamed for Reeva and went to look for her.
Through tears, Pistorius says: "I was scared of entering the bathroom again."
12:18 GMT - 'Blame myself' - "Who do you blame for the accident?" asks Nel.
Pistorius is turning red in the witness stand and appears unable to compose himself, AFP's Stephanie Findlay tells us from the courtroom.
"I blame myself for taking Reeva's life," says Pistorius.
12:16 GMT - Accident? - "Did you fire to shoot the intruder?" asks Nel.
"No I did not my lady, I fired because I got a fright," says Pistorius.
"And it was all an accident?" asks Nel. "If there was in fact an intruder and you shot and killed an intruder, would that be an accident?"
"Yes my lady," says Pistorius.
12:15 GMT - Shooting position - "When you fired the shots, can you just indicate to the court where your gun was?" asks Nel.
Pistorius holds his arm straight forward, slightly bent at the elbow. "It's not the normal shooting position," he says.
12:03 GMT - Resumption - The court is back after lunch and Nel goes in hard.
"Mr Pistorius, what did you think would happen when you fired through the door?" asks the prosecutor.
"I didn't have time to think," replies Pistorius.
11:29 GMT - In summary - As the court continues its lunch break, here is a recap of the main points from this morning's evidence:
-Prosecutors alleged Pistorius argued with Steenkamp just before shooting her dead. "It's the state's case, Mr. Pistorius, that she wanted to leave and that you weren't sleeping, you were both awake," said prosecutor Gerrie Nel. Pistorius said that was "untrue".
-Pistorius sobbed loudly when insisting that he did not fire at Steenkamp, forcing a brief adjournment. He insists he was firing at the bathroom door.
-Nel repeatedly described the athlete's explanation that he accidentally shot through the locked door as "so improbable that it cannot be reasonably possible".
11:02 GMT - Adjournment - Court breaks for lunch after another morning of exhaustive cross-examination for Oscar Pistorius.
10:57 GMT - Scream test - Pistorius says he has done a scream test as part of the legal process which was recorded at his current residence.
"Don't you think it would be prudent to play the recording so the witness could say that's what they heard?" asks Nel.
Roux taps his fingers on the defence benches as Judge Masipa intervenes, telling Nel to lay off Pistorius.
"I can't remember what I sounded like that night," said Pistorius. "I was screaming for the Lord to help me, I ran onto the balcony... and I don't think one scream was the same."
10:50 GMT - Screaming - Nel is questioning Pistorius about evidence from his neighbours about hearing screaming.
Nel asks: "Between the first shot and the second shot, there was screaming. Was that you?"
Pistorius says: "Which series (of bangs), the first or the second?"
After further exchanges, he says he was screaming and adds his voice "can be of a high pitch."
10:47 GMT - Door locking? - Using the door which is in court, Captain Mike Van Aardt demonstrates the sound the toilet key makes when it locks, a definite clank of metal.
Nel asks Pistorius if he heard that sound. Pistorius says no.
He is looking extremely uncomfortable in the witness stand, Stephanie Findlay tells us.
10:43 GMT - Quiet voice - The judge has repeatedly told Pistorius to speak up. He talks extremely softly and faces away from the gallery. When he breaks down, his words are not discernible at all.
Journalists in court are actually taking down quotes while listening to the trial's live audio feed over the internet, Johannes Myburgh tells us.
10:40 GMT - Aim - Nel claims that one of the bullets hit Steenkamp and she fell on to the magazine rack.
"The magazine rack, we know you heard it, that's why you changed your aim," says Nel.
"That's not true," says Pistorius.
"You never aimed, you aimed at the door, am I right?" says Nel. "You just pointed your gun in your right hand towards the door."
"That is correct my lady," says Pistorius.
"And you discharged the firearm," adds Nel.
10:35 GMT - Toilet photo - Nel now shows a photo of the bathroom to the courtroom with the trajectory of bullets coming through the door.
10:33 GMT - Magazine rack - "I heard a noise coming from the toilet which I perceived was the door opening," Pistorius says.
Nel tells him he is not interested in his perception but by what actually happened.
"In retrospect, I probably heard a magazine rack moving," Pistorius says.
10:28 GMT - Defence case - AFP's Johannes Myburgh tells us that Pistorius's reason for firing at the bathroom door is key to his defence.
"Up to now it was putative self-defence: by his version, the sprinter thought he was firing at an intruder who was coming to attack him," Myburgh says.
"The problem with this is he has to prove his life was in danger or that he had good reason to think so, and it is difficult to argue that if the door was closed and he only heard noises.
"That is why the defence has put so much emphasis on his paranoia over crime -- he is so afraid of being attacked that those were his thoughts that night. If he had fired at an actual intruder under the same circumstances, he could still be convicted of murder.
"However, under cross-examination, Pistorius has said he fired by accident, that it was involuntary. This is a change in his argument. Yet it seems he has not officially changed his defence, so it is not clear why the athlete is saying this."
10:22 GMT - Back in court - The trial resumes with Pistorius back in the dock and seemingly having composed himself.
Prosecutor Gerrie Nel addresses Judge Masipa, suggesting Pistorius is not simply getting emotional but perhaps seeking to delay proceedings.
10:08 GMT - 'Defence changed' - Before the break, Nel accused Pistorius of changing his defence.
"Your defence had changed. It is not self-defence, it is involuntary action," says Nel. "It's now 'I don't know why I fired.'"
"I thought someone was coming out to attack me," says Pistorius.
But Nel highlights that Pistorius said he didn't fire at a person.
"I fired in the direction I thought the threat was coming from," says the runner.
"You know exactly, you fired at Reeva," says Nel.
It was this accusation which prompted Pistorius's emotional insistence that he did not fire at his girlfriend.
10:02 GMT - 'Did not fire at Reeva' - "Is it your defence that you fired at the attacker?" says Nel.
"No my lady," says Pistorius.
"Or did you fire at the perceived attacker?" says Nel.
"I fired at the door my lady," says Pistorius.
Shortly afterwards, under questioning, Pistorius sobs loudly as he insists: "I did not fire at Reeva."
The trial takes a break.
10:00 GMT - Set to fire - Nel seems to be probing Pistorius's intent at this stage -- whether he was preparing to fire.
"Were you aiming at the door or pointing the gun at the door?" says Nel.
"That's right my lady, I didn't aim at the door, my firearm was pointed at the door," says Pistorius.
09:56 GMT - Noise from toilet - "Then I heard a noise from the toilet," Pistorius says.
"What did you hear?" asks Nel.
"It sounded like the door opening, it sounded like a wood movement," he replies.
He adds that he fired as he heard the noise.
09:51 GMT - Not included - Nel demands to know why the detail about the noise of the door shutting was not in Pistorius's bail affidavit or plea explanation.
"I'm not sure," Pistorius says.
09:48 GMT - Toilet door - "Did you hear the toilet door slam shut before or after you screamed at Reeva?" asks Nel.
"I heard the door slamming whilst I was shouting and screaming," says Pistorius.
Nel asks why he didn't give that evidence previously.
"I'm not sure," said Pistorius, a phrase he has used repeatedly this morning, AFP's Stephanie Findlay reports.
09:44 GMT - 'Something you forgot' - "As I came around the corner to the closet, I stayed as far away as I could from the wall," says Pistorius. "I peered into the bathroom."
"My eyes were checking the window frame in the door at the same time," he adds.
His lawyer Barry Roux is still, with a pen in his mouth.
"But there's something very important that you forgot that happened there," says Nel. "The door slammed."
"That happened in the passage," says Pistorius, growing indignant.
"Why didn't you mention it?" asks Nel.
Nel says Pistorius never said the door slammed, Pistorius disagrees, but Nel insists -- and says the record will prove -- Pistorius is wrong. Still, Pistorius argues.
"Mr Pistorius, I put to you that it's not so, and I'm willing for you to listen to the record," said Nel.
09:42 GMT - Firearm - Nel asks Pistorius to show the court how he was holding the gun.
Pistorius raises his right arm, bent 90 degrees, his fist clenched.
"My firearm was in front of me," says Pistorius, his voice shaking.
09:34 GMT - Why emotional? - Nel is also asking Pistorius why he got emotional after he asked him to recall what he said to the intruder.
Pistorius looks pale in the witness stand, his shoulders are hunched.
09:33 GMT - Hearing resumes - The hearing restarts and Nel is back asking questions about the night of the shooting.
Pistorius tells the court again that he called for Steenkamp to call the police.
08:55 GMT - 'Get out' - Nel asks Pistorius if he remembers what he screamed at the intruder in the bathroom.
"I screamed, I said 'get the f--- out of my house," says Pistorius, his voice pitching high, "get the f--- out of my house."
Judge Masipa adjourns court as the athlete breaks down crying, his face red.
Pistorius's sister Aimee rushes up to the witness stand to console her brother.
08:53 GMT - Scared? - Nel asks questions about what the athlete was thinking at this stage, Stephanie Findlay tells us.
"You were scared, you thought there were intruders in the house?" he asks. "That's how you approached them, with a bent arm and your gun at the side... what did you achieve?"
"I wanted to chase the people out of my house, my lady," says Pistorius.
"Could you see something?" asks Nel.
"I could see a little bit of light," says Pistorius, his voice starting to break.
Steenkamp's mother, sitting beside Reeva's half-sister, has kept her head bowed through the majority of the proceedings this morning.
08:49 GMT - Gets gun - Pistorius says he froze when he heard the noise.
"I then collected my firearm from under my bed... as I started walking, I told Reeva to get down on the floor and call police," he adds.
08:44 GMT - Window slamming? - Nel is questioning why Pistorius didn't mention the window "slamming" in his bail application.
"Why is the big issue of the window slamming into the frame not mentioned?" Nel asks.
"I'm not sure my lady," Pistorius responds.
The athlete later insists: "There's no tailoring of my evidence."
08:40 GMT - Analysis - AFP South Africa correspondent Johannes Myburgh (@johannesmyburgh) tweets: "#OscarTrial cross-examination this morning along lines of: 'Your version is so improbable that it cannot be reasonably possible.'"
08:36 GMT - Bathroom window - Nel tells the court: "I want to take you to the first time you heard a noise in the bathroom. You picked up the jeans, you were about to cover the light when you heard a noise in the bathroom, is that right?"
Pistorius identifies the noise he heard as coming from the window opening and hitting the window frame.
08:27 GMT - Whisper or soft voice? - Nel is grilling Pistorius on whether he spoke softly to Steenkamp or whispered to her to get down and call the police.
He is trying to highlight apparent inconsistencies in his evidence.
"I'm just more concerned with the fact that you would convincingly deny that you whispered on more than one occasion," he says, highlighting that Pistorius's evidence in chief said he whispered.
"I must have made a mistake," Pistorius says.
08:25 GMT - Duvet - Nel returns to the placement of the duvet and the fan in the bedroom after Pistorius shot Steenkamp. The state alleges that Pistorius is not being truthful about his version of events.
Pistorius says that police moved key pieces of evidence -- including the duvet and fans -- when they arrived at the crime scene.
"Don't you want to admit, Mr Pistorius, that at least you made a mistake that the duvet was on the floor?" says Nel.
"I don't remember the duvet being on the floor," says Pistorius.
Nel says that as long as Pistorius keeps on arguing, things will get worse for him.
"Is there something wrong with you, Mr Pistorius?" says Nel.
"My eyes are sore, my lady," says Pistorius. Judge Masipa takes sympathy on the athlete, saying she noticed him touching his eyes earlier.
Nel continues his questions. "The policeman either by design or luck put the duvet on the floor where that particular corner in line with the blood splatter on the carpet, is that what you're saying is possible?"
Pistorius says no.
08:15 GMT - 'You have to create time' - Nel is hammering Pistorius about the blue LED light on his amplifier.
"Why would you not remember that, why do you have a memory loss as far as that's concerned?" asks Nel.
"I remember picking up the jeans and covering the light…that's what I remember," says Pistorius.
"You have to, Mr Pistorius create time, you have to, on your version, build a time gap for Reeva to get to the bathroom, that's why you invented what you're doing now," said Nel.
"Otherwise that whole amplifier would have bothered you," said Nel.
Pistorius becomes defiant.
"The state has been trying to create time in their evidence, in Samantha Taylor's evidence she said it took four minutes to put my legs on, I'm not trying to buy time," says Pistorius.
"No, you see Mr Pistorius, it's all these small things because if we go up one, we see not only is the amplifier on, the disc player is also on," says Nel.
08:08 GMT - Amp light - Nel is questioning Pistorius in detail about an LED blue light from an amplifier in the darkened room.
He asks why, in the cross-examination of state witnesses, defence lawyer Roux did not talk about it.
"And the fact that the blue light was never put to Colonel Van Rensburg or Van Staden, the photographer, am I right?" says Nel.
Nel points out the amplifier has other lights on it and asks Pistorius why that blue light bothered the athlete but not the others didn't.
"No my lady, the LED light, that whole panel, there is a display panel but the light inside the switch on the far left is the light that bothered me, my lady," says Pistorius, emitting a deep sigh.
08:05 GMT - 'Is anything wrong?' - Pistorius repeatedly answers he is "not sure" to Nel, who hones in on the response.
"Today I pick up you're not sure about things, is anything wrong?" asks Nel. "You're fine?"
Pistorius says he's fine.
08:04 GMT - Fan - Nel is questioning Pistorius on the testimony of a state witness who said the fan was directly in front of Pistorius's bed, Stephanie Findlay in court tells us.
He asks Pistorius why he did not mention the fan was in front of the bed in any of his statements, and accuses him of tailoring his evidence.
"Why during all that time did Mr Roux did not put the fan in front of the bed to where you say it is?" asks Nel.
"I'm not sure my lady," said Pistorius.
"Because it's not your version, it was never your version, it was a tailored version during cross examination," says Nel.
"That's not true my lady," said Pistorius.
07:58 GMT - Crime scene - Nel is questioning Pistorius on police arriving at the crime scene after he shot Steenkamp.
He is specifically asking him about evidence from Colonel Schoombie van Rensburgh that he had gone up to the scene first.
"I don't know I can neither confirm or deny, my lady," says Pistorius, growing increasingly uncomfortable.
"Even during cross-examination, you were asked where his focus was and he said that inter-alia his focus was on the fan in front of the door," said Nel. "You cannot deny that."
Nel turns back and talks to police photographer, before turning back to Pistorius.
07:44 GMT - Jeans - Nel is asking Pistorius why Steenkamp's jeans were out of her impeccably-packed bag.
"I'm saying, and it's the state's case Mr Pistorius, that she wanted to leave and that you weren't sleeping, you were both awake," he says.
"That's not correct my lady, that's untrue," replies Pistorius.
"And that there was an argument," responds Nel.
07:36 GMT - Start - Prosecutor Gerrie Nel is starting out, as he always has, strongly.
"Your version is so improbable that it cannot be reasonably possible," he tells Pistorius.
07:29 GMT - Reeva's mother - Reeva Steenkamp's mother June -- who must have undergone a traumatic time listening to this evidence -- is also in court again today.
She is sitting next to a member of the ANC Women's League.
07:27 GMT - Arrivals - Pistorius has arrived at court and is sitting in a seat by the dock.
He appears to have had a buzzcut haircut, his hair close to his head, AFP's Stephanie Findlay tells us.
His defence lawyer Barry Roux is sitting in a chair, chatting with another member of his team.
Sister Aimee has arrived to court, sitting with her aunt in the first row of the public gallery.
07:17 GMT - WELCOME to AFP's Live Report on Oscar Pistorius's fourth day of cross-examination in a trial where he is accused of murdering his girlfriend Reeva Steenkamp on Valentine's Day last year.
The South African Paralympian has been facing aggressive questioning from prosecutor Gerrie Nel, who is seeking to prove that Pistorius knowingly shot his partner through a locked bathroom door at his home.
The double-amputee, who has cried and retched as he gives evidence, insists it was an accident and that he thought there was an intruder.