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Pistorius faces brutal cross-examination

WARNING GRAPHIC IMAGES: a gruesome photo of Reeva Steenkamp's head wound is shown during Oscar Pistorius' murder trial.

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London: Reeva Steenkamp's mother doesn't know if Oscar Pistorius' distress is an act, but insists the athlete has gone "from hero to devil" after killing the 29-year-old model on Valentine's Day last year.

South African Olympic and Paralympic star Pistorius has faced fierce cross-examination during his murder trial, with the prosecution demanding he admit his girlfriend's death was more than just a "terrible mistake".

June Steenkamp after her dead daughter's picture was shown in court.

June Steenkamp after her dead daughter's picture was shown in court. Photo: AFP

Prosecutor Gerrie Nel on Wednesday said: "You killed a person, that's what you did. You shot and killed her, won't you take responsibility for that?"

Steenkamp's mother June has attended each day of Pistorius' trial in Pretoria.

"It's very traumatic when certain things come up," she told British tabloid the Daily Mirror. "This is my child - and I must listen to the graphic detail ... I look at Oscar the whole time, to see how he is coping, how he is behaving. I'm obsessed with looking at him, it's just instinctive, I can't explain it."

Oscar Pistorius leaves court in Pretoria on Wednesday.

Oscar Pistorius leaves court in Pretoria on Wednesday. Photo: AP

Ms Steenkamp, 67, said the athlete's courtroom demeanour had been very dramatic with "the vomiting and crying".

"I don't know whether he's acting," she said. "Most of the time he's on his mobile phone or looking down at papers or writing notes."

The heartbroken mother feels her presence unnerves Pistorius because he's answerable to her.

Reeva Steenkamp in January last year.

Reeva Steenkamp in January last year. Photo: AFP

"I don't know the man. All I know is what he's done," she said. "He must see me there in the court, he must feel my eyes boring into him, I think it makes a lot of difference."

Ms Steenkamp admitted she probably looked at the 27-year-old too much to see how he was reacting. But she added: "I don't care what happens to Oscar, I don't even care if he goes free.

"All I know is that he has to stand up to what he's done and - if he has to - pay for it ... What difference is it going to make to me if he goes to prison for 25 years or is allowed to walk free?"

Ms Steenkamp said Pistorius had an aggressive persona and was used to people adoring him.

"So it must be pretty different for him now," she said. "He's been spoilt by other people, that's why he struts around and looks superior. He's gone from hero to devil."

Pistorius claims he mistook Reeva Steenkamp for an intruder.

AAP