Oscar Pistorius's lawyer accused a State witness on Wednesday of tailoring his testimony to fit that of his wife and prejudice the athlete accused of murdering his girlfriend.

Charl Johnson has told the High Court in Pretoria the couple were woken by a woman's anguished screams on the night Reeva Steenkamp died, and returned to the witness stand for cross-examination on Wednesday.

Barry Roux, for Pistorius, charged that the soft-spoken IT expert had failed to give the court an independent version of what he heard in the early hours of Valentine's Day last year, when Steenkamp died.

"You have not favoured the court with a strong, independent version," Roux told Johnson.

"What worries me... This court really is entitled... that witnesses come to court not contaminated. Maybe you and your wife should have stood together in the witness box."

Judge Thokozile Masipa intervened and asked Roux: "Aren't you going a bit far?"

Roux conceded and dropped that line of questioning.

But he has consistently tried to cast doubt on the credibility of the couple who live in a townhouse 177m from the one where Pistorius fatally shot Steenkamp through a locked toilet door -- by his submission because he mistook her for an intruder.

Both husband and wife have given the court dramatic accounts of being woken around 3am by a woman calling for help, followed by a man's voice and a volley of gunfire.

As he did with Johnson's wife, first State witness Michelle Burger, the seasoned advocate suggested he mistook for gunshots the sound of Pistorius breaking the door behind which Steenkamp died with a cricket bat.

"I understand your believing that the noises you heard were gunshots," Roux said.

"But there are problems with your belief... A man's life is at stake."

Earlier, Roux had noted "remarkable coincidences" between Johnson's statement to police and that of his wife.

Roux sought to make the same point on the first two days of the trial when he cross-examined Burger for hours.

She remained composed and rejected any notion of bias or inconsistency.

Only later, when State prosecutor Gerrie Nel asked how she had felt after the shooting, did Burger break down and say she was traumatised for months by the memory of Steenkamp's screams.

The State will try to prove that Pistorius committed premeditated murder, and a conviction on that charge could see the disabled athlete nicknamed "Blade Runner" jailed for life.

In addition he is charged with illegal possession of a firearm and ammunition, and recklessly discharging a firearm in public. He has pleaded not guilty.

The trial is being televised live and Johnson conceded on Tuesday that he and his wife had been loathe to brave the media spotlight but felt compelled to go to the police after it became apparent during Pistorius's bail hearing that his version was inconsistent with what they had heard.

The witnesses have all requested that their faces not be photographed or shown on television.

But on Wednesday, Johnson revealed that he had received a number of distressing messages after his cellphone number was read out in court on Tuesday.

One message inquired why he was lying about what happened on the night that Pistorius shot Steenkamp.

The State has indicated it could call more than 100 witnesses and one of Pistorius's former girlfriends, Samantha Taylor, was seen arriving at the court on Wednesday.

Shortly after the shooting, Taylor came forward, saying Pistorius had previously fired a gun through the open sunroof of her car.

Also in court was boxer Kevin Lerena who was with Pistorius in a restaurant when he accidentally fired a gun.

That incident occurred days before Steenkamp's death.