In a dramatic second day of testimony, a distraught Pistorius told a Pretoria court that he suspected intruders had climbed into the second storey bathroom through a window when he used a handgun to shoot into the locked room.

“I started screaming again for Reeva to call the police … I wasn’t sure if someone was going to come out of the toilet to attack me.

“So I just stayed where I was and kept on screaming. And then I heard a noise from inside the toilet that I perceived to be someone coming out of the toilet and before I knew it I’d fired four shots through the door.”

Pistorius said the first gunshot left his ears ringing, preventing him from hearing anything.

“I lifted myself up to the bed and placed my hand to the right hand side of the bed and I felt if Reeva was there and I couldn’t feel anything … It was at that point it first dawned on me that it could be Reeva inside the toilet.

 I didn’t want to believe that it could be Reeva inside the toilet.

“I couldn’t see much in the room. I still had my firearm with me. I didn’t want to believe that it could be Reeva inside the toilet.

“There was a big plank [from the door] that I threw across the bathroom. I tried to open the door from inside. I unlocked the door. I saw Reeva and sat over her and cried. I don’t know how long I was there for.”

At this point Pistorius completely broke down in sobs and tears. Defence lawyer Barry Roux said he could not “responsibly ask the court to carry on today. I saw the accused outside… and his shirt was soaking wet.”

June Steenkamp, mother of murdered model Reeva.

Earlier on Tuesday, the athlete known as the Blade Runner described how he met the model at a track day car event.

“The first six days we knew each other we called each other every day,” he said.

“I was very keen on Reeva,” he said. “I think if anything I was more into her, than she was at times with me.

“We started really seeing a future with each other,” he said.

Called as witness in his own defence, Pistorius has insisted he and the 29-year-old law graduate, model and aspiring actress had a loving relationship and sought to explain text messages in which Steenkamp said she was scared of him.

“I just think it was a bad hour in our relationship,” he said, describing a fight at an engagement party.

Steenkamp had sent Pistorius a message saying: “I’m scared of you sometimes and how you snap at me and how you will act towards me.”

I’m scared of you sometimes and how you snap at me and how you will act towards me.

Steenkamp’s mother, June, attended Tuesday’s hearing along with Steenkamp’s friend, Gina Myers, who was wearing tags that bore a black-and-white print of the model.

On Monday, Pistorius had made a tearful apology to Steenkamp’s family.

“I can promise that when she went to bed that night she felt loved,” he said choking back tears, his voice faltering.

“There isn’t a moment, or hasn’t been a moment since this tragedy happened that I haven’t thought about your family.”

Pistorius’s initial evidence has focused on countering the prosecution’s portrayal of him as reckless and obsessed with fast cars and guns.

He has spoken of a difficult childhood, exposure to crime and challenges of his disability.

A bucket was placed next to Pistorius in the courtroom.

He is likely to remain on the stand most of the week as his extensive testimony is expected to be following by gruelling and likely lengthy cross-examination.

Besides answering a charge of murder, Pistorius also has to testify about three unrelated charges: two of firing a gun in separate incidents and one for the possession of illegal ammunition, found in a safe at his home.

Cape Town-based criminal advocate William Booth said much will depend on how Pistorius stands up to cross-examination.

“Oscar’s evidence can only be properly assessed once he’s been cross-examined,” Booth said.

In the five weeks since the trial began, Pistorius has appeared fragile and sometimes annoyed, frequently crying in court.

Pistorius accompanied by his relatives outside court.

He was physically sick when the gruesome details of Steenkamp’s death were discussed.

Pistorius has hired an extensive team of forensic experts, including an American animation firm that will visually depict the crime scene using three-dimensional computer-generated images.

The experts will have to cast doubt on the state’s version of events, including testimony from witnesses who said they heard a woman screaming on the night of the killing, which would show Pistorius knew his target was Steenkamp.

The trial is slated to run to at least mid-May.

-with AAP