Oscar Pistorius' defence team says claims by a neighbour that she heard a woman's screams after Reeva Steenkamp was shot will be thrown into doubt by expert evidence.

The claim came on an emotional day in court, in which Pistorius was seen wiping his eyes with a white hankerchief, and the prosecution's key witness wept.

Neighbour Michelle Burger, who says she heard Ms. Steenkamp being killed by Pistorius, was grilled by the athlete's defence team for a second day.

She told the packed courtroom in South Africa's administrative capital Pretoria she heard a woman screaming as shots were being fired in Pistorius' residence.

But Pistorius' lawyer Barry Roux said "We will debate the sequence of the bullets. We will have experts state that there was serious brain damage after the shot to the head, that it would not have been possible for her to scream at all".

Ms. Burger replied "As I said yesterday, I heard her voice just after the last shot. It could have been that it was as the last shot was fired".

The prosecution later said that had the head shot been the final shot, Ms. Steenkamp could have screamed until then.

Mr. Roux opened Tuesday's questioning by saying he wanted to focus on two aspects of Ms. Burger, her "credibility and reliability".

Mr. Roux has repeatedly attempted to establish this morning that Ms. Burger had already decided she did not believe Pistorius' account of the evening - that he believed there was an intruder in his home when she gave her evidence contradicting his story.

She is the prosecution's key witness, as her account of hearing a woman's screams suggests Pistorius would have known that it was his girlfriend rather than an intruder when he fired.

A tense exchange between Mr. Roux and Ms. Burger came to a climax when he said he had asked her the same question eight times.

"I'm going to be really slow this time" he said. "You heard at the bail application that it was put on behalf of Mr Pistorius that Reeva did not scream that night, is that correct?"

After giving an unclear answer, Judge Thokozile Masipa intervened and insisted that she had to give a clear answer. Eventually, the witness admitted she had heard about Pistorius' claims.

Mr. Roux said: "You've watched Sky News, you've watched other channels, and you've got retrospective knowledge and you take that knowledge and you come and give evidence today as if it's the knowledge of that fateful evening".

Ms. Burger, who had been composed through two days of aggressive cross-examination, wept as she finished her testimony. She then broke down as she recalled the "raw emotion" she felt after the killing.

She told defence lawyer Barry Roux about the statement she gave police after the death.

At around the same time, Pistorius was seen reaching for a hankerchief from his inside pocket and wiping his eyes.

Later, Ms. Burger's husband Charl Peter Johnson took to the witness stand. He said "We were under the impression that they were being held up in their house".

"I lay in bed thinking of how I can improve the security around my house. I fell asleep at about 4am. When I woke up I started measuring around the house. I went to work early around 6am and I remembered surfing on the web for security gates for costs".

A second neighbour has also told the murder trial she was woken by loud voices on the night of the shooting.

Estelle Van Der Merwe - who lives opposite the Paralympic medalist's home in Pretoria - claims she heard gunshots followed by crying on Valentine's Day last year.

Speaking through a translator, she told the court about the moment she later discovered what had happened.

Earlier, the trial was temporarily delayed after an image of the witness was used by a South African news organisation. The trial is being televised, but witnesses can choose not to appear on camera.

The case was temporarily adjourned just before 8am after Judge Masipa was alerted to an image of the witness that had appeared in local media.

The judge said she viewed the error as "serious" and ordered an investigation.

Pistorius, a double-amputee, is accused of the premeditated murder of Ms. Steenkamp last Valentine's Day after a jealous row.

He is also accused of the illegal possession of ammunition and two additional counts relating to shooting a gun in public in two separate incidents before the killing.

Pistorius (27), who is known as the Blade Runner, denies all the charges against him. He claims he shot his girlfriend by mistake at his home after mistaking her for an intruder.

The trial, large parts of which can be broadcast live after a landmark ruling, is scheduled to last for three weeks and will hear from more than 100 witnesses.

South Africa does not have a jury system. Instead, Judge Masipa will decide his fate. If Pistorius is found guilty he could be jailed for at least 25 years.