The judge in the murder trial of Oscar Pistorius has warned the media to behave after a local television station leaked a photo of the state's first witness who had asked that her image not be broadcast.

Judge Thokozile Masipa ordered an investigation into the leak after broadcaster eNCA showed a photo of Mr Pistorius' neighbour Michelle Burger during the audio broadcast of her second day of testimony.

While the trial is being televised live, a previous court order had ruled witnesses must give their consent to be filmed.

Television station eNCA today accompanied the audio broadcast with a picture of Ms Burger.

After prosecutor Gerrie Nel pointed out the leak, Judge Masipa called for a brief adjournment.

"I am warning the media, if you do not behave, you are not going to be treated with soft gloves by this court," Judge Masipa, herself a former journalist, said when the court resumed.

Mr Pistorius, a 27-year-old Olympic and Paralympic athlete, is on trial for murdering his girlfriend, model Reeva Steenkamp, at his suburban Pretoria home on St Valentine's Day last year.

He says he mistook her for an intruder.

Ms Burger, a university lecturer who testified yesterday that she heard "bloodcurdling" screams from a woman followed by gunshots, has not consented to being filmed and only the audio of her testimony is being broadcast.

She was closely cross-examined for a second day on her testimony by lead defence attorney Barry Roux.

Mr Roux read out details from the post mortem, including that "some fragments of the bullet" were removed from the 29-year-old's head.

He also heaped scorn on the testimony of Ms Burger, who said she heard a scream fade away after the shots.

He said that Ms Steenkamp would have "dropped immediately" due to a bullet in the head.

Ms Steenkamp was declared dead at the scene after being hit in the head, arm and hip from three bullets from a 9mm pistol.

Ms Burger broke towards the end of her own testimony, following an angry exchange with Mr Roux, who had sought to show she had mistaken the screams of an agitated Mr Pistorius for that of a woman.

The court also heard from another neighbour, Estelle vander Merwe, who testified that she heard what sounded like an argument early on the morning Ms Steenkamp was killed.

"From where I was sitting, it seemed like two people were having an argument but I couldn't hear the other person's voice," she said through an Afrikaans language interpreter.

Judge Masipa has also restricted the media from publishing photos of witnesses who have not consented to be filmed.

Patrick Conroy, the head of news at eNCA, said on Twitter the station had used a photo from the website of the University of Pretoria, where Ms Burger is a lecturer of construction economics.

Other newspapers also used the picture, he said.

However, he apologised in a statement, saying it was a "bad judgement call" to use the photo.

A separate South African court ruled last month that the trial should be televised, saying it was vital for impoverished South Africans who feel ill-treated by the justice system to get a first-hand look at the proceedings.

Steenkamp's mother: Pistorius didn't look me in the eye

Meanwhile, Ms Steenkamp's mother, June, has said Mr Pistorius walked straight past her in court yesterday, denying her the opportunity to look him in the eye.

Speaking to the US channel NBC, Mrs Steenkamp said Mr Pistorius never made eye contact with her on the first day of his trial for murdering her daughter.

"He just walked into the courtroom and looked straight ahead. And then he sat down and never looked my way," she said.

"I wanted him to see me. I'm the mother of Reeva," said the 67-year-old, who travelled from the southern coastal town of Port Elizabeth to attend the trial in Pretoria.

She said it was important that he saw her in court. "I can't explain to you why, that's what I wanted to do today."

Mrs Steenkamp was not in court today. She added that her husband Barry, who suffered a minor stroke last month, could not travel to Pretoria.

She said she had never met Mr Pistorius and Reeva's relationship with the double-amputee sprinter was brief.

"I think it was three months," she said.

"I just want the truth. We want the truth of what happened. Only she and Oscar were there and she's not here anymore."

Mrs Steenkamp said she wanted the truth on what happened on the night her daughter was killed, adding that it was important to forgive the Paralympic gold medal star.

She said: "I've got to depend on the justice system that we get justice and we get answers. I've got confidence in that.

"It doesn't matter what happens to Oscar because my daughter is never coming back.

"It's actually important to forgive him, for me. Because I don't want to live with bitterness in my life. I can forgive."