Prosecutor Gerrie Nel told Oscar Pistorius "I'm not going away" as he picked through the disabled runner's evidence and accused him of lying.

Cross-examining the Olympian and Paralympian, Nel tried to discredit his version of events and his plea of not guilty to murdering Reeva Steenkamp.

Nel went on the attack by accusing Pistorius of being evasive in his answers about the location of two fans in his bedroom on the night he killed the model, 29.

Pistorius admitted his testimony at various times since the killing contained inconsistencies, but insisted they had been made in good faith due to "pressure."

When the 27-year-old runner challenged the line of questioning by calling it "insignificant," Nel hit back: "It will show that you are lying and it is very significant."

The lawyer went forensically through the runner's story about turning off two fans before shooting dead Steenkamp, on Valentine's Day last year.

Nel claimed Pistorius had made up the event. During examination of his bail application, plea statement and earlier testimony, Pistorius admitted there were inconsistencies, blaming them on related stress.

Nel claimed the fans had never been plugged in and produced photographs from the scene showing the uplugged fans next to power extension leads with no space available for more plugs.

Pistorius alleged the fans were among a horde of items at the scene which had been "tampered with" in the aftermath of Steenkamp's death.

The runner was giving evidence at his murder trial for a third straight day and Nel was apparently frustrated at times by the manner of the defendant's answers.

On one occasion, Nel said: "You're sitting there arguing, thinking up evidence, not answering questions. Mr Pistorius, please answer the questions. If you think about other evidence you will get in trouble."

Nel repeatedly reminded Pistorius of what he had done to Steenkamp during cross-examination, as he appeared to grow frustrated with the athlete's responses.

When Pistorius admitted he was thinking through the implications of his replies to Nel's questions because his life was "on the line," the lawyer hit back sharply: "But Reeva Steenkamp doesn't have a life because of what you've done. She does not have a life anymore because of what you've done. So stop thinking of yourself and tell the truth."

When Pistorius looked like he was starting to crack beneath the onslaught, Nel asked: "Why are you emotional now the questions are difficult?"

Earlier in the day, Nel shocked Pistorius by showing a gory image of the model's head with a bloody bullet wound in it.

The day's proceedings ended with the runner claiming he had not deliberately fired his gun through the door of the bathroom in his luxury home, on the outskirts of Pretoria.

Pistorius denies murder and claims he mistook Steenkamp for an intruder. The prosecution alleges he killed her following an argument between the couple.

The trial continues.