Oscar broke down in court on Tuesday as he heard a first and second witness give their statements.
Second witness neighbour Estelle van der Merwe, who lives just under 100metres away from Oscar's home, said that she woken at just before two in the morning by a row, which went on for about an hour before shots were fired.
Estelle, who was described as more timid and less confident than Monday's first witness Michelle Burger, stated that she heard people "talking in loud voices" and then heard four gunshots at around 3am. After this, Estelle said that there was "total silence" followed by a "commotion" and "someone crying out loudly."
"I asked my husband who was crying like that and he said it was Oscar," she said. "To me, it sounded like a woman's voice."
THE TRIAL SO FAR...
State prosecutors have maintained that Oscar intentionally shot his girlfriend several times through the bathroom door, after they had an argument in the early hours of the morning.
The double-amputee athlete gave a statement at the start of the trial denying all charges, and pleaded not guilty to the "wilful and intentional murder of Reeva Steenkamp". Oscar has previously claimed that he mistook the late model for a dangerous intruder.
The court was read a statement by Oscar's lawyer, in which Oscar claimed that he and Reeva had been lying in bed, when he went out to bring in some fans from another room.
"Unbeknown to me, Reeva must have gone to the toilet in the bathroom at the time when I brought in the fans, closed the sliding doors, and drew the blinds and the curtains," the court heard.
"I heard the bathroom window sliding open. I believed that an intruder or intruders had entered the bathroom through the bathroom window, which was not fitted with burglar alarms. I approached the bathroom armed with my firearm so as to defend Reeva and I. At that time I believed Reeva was still in the bed.
"The discharging of my firearm was precipitated by a noise in the toilet which I, in my fearful state, knowing that I was on my stumps, unable to run away or properly defend myself physically, believed to be the intruder or intruders coming out of the toilet to attack Reeva and me."
Wearing a dark suit and tie, Oscar remained calm and neutral as he stood before the judge and court on Monday – a far cry from his emotional appearance at the bail hearing last August in which he broke down in tears.
The court heard from the first witness, Oscar's neighbour Michelle Burger, who described being woken by "a woman's terrible screams" at three in the morning.
"She screamed terribly and she yelled for help," said Michelle. "Then I also heard a man screaming for help. Three times he yelled for help. Just after her screams, I heard four shots. It was very traumatic for me. You could hear that it was bloodcurdling screams."
Oscar's defence lawyer Barry Roux questioned the witness, asking whether she may have heard a cricket bat being used to break down a door rather than gunshots.
"I am 100 per cent certain I heard gunshots that evening. I know what one sounds like," said Michelle, adding how she couldn't understand how Oscar had not heard any screaming. "The fear in that woman's voice. You only fear like that if your life is threatened."
Oscar broke down in tears, rubbing the back of his neck and wiping his eyes with a tissue, when Mr Roux explained to Michelle at Tuesday's session that she could not have heard a woman scream after shots were fired, as Reeva was shot in the head – a catastrophic injury that caused "serious brain damage" and rendered her unable to make a sound.
Reeva's family, including her mother June, watched the trial from the relatives' bench, while Oscar's uncle, brother and sister also sat in court.
If found guilty of premeditated murder, Oscar could face life imprisonment. The athlete has also been charged with illegally possessing ammunition.
As there are no juries at trials in South Africa, the final decision will be made by Judge Thokozile Matilda Masipa.
Given the intense media and public interest in the star's case, parts of the trial will be televised. One South African TV station, MultiChoice, set up a dedicated Oscar Pistorius Trial channel to provide 24-hour coverage.