A member of the defence legal team reaches out to Olympic and Paralympic track star Oscar Pistorius as he holds his head while a witness testifies during the fourth day of his trial for the murder of his girlfriend Reeva Steenkamp. REUTERS/Marco Longari/Pool

Pretoria - The first doctor to arrive at the scene where Oscar Pistorius shot Reeva Steenkamp testified on Thursday that the athlete was so emotional he feared he would turn the gun on himself.

“I was afraid Oscar would hurt himself,” radiologist Johan Stipp told the High Court in Pretoria, where Pistorius earlier this week pleaded not guilty to premeditated murder.

Stipp, a neighbour of Pistorius's in the plush Silver Woods security estate, said he was woken by gunshots and screams in the early hours of February 14 last year, and after alerting security, went to see if anybody needed medical help.

He found Pistorius kneeling next to his dying girlfriend, with one hand on a bullet wound in her thigh and the other in her mouth, trying in vain to force her to breathe.

Pistorius words to him were: “I shot her. I thought she was a burglar and I shot her.”

Describing the athlete's distress, he told the court: “He was praying. He was talking to God ... He was trying, maybe I don't know, to get atonement.

“He definitely wanted her to live... He looked sincere to me. He had tears on his face,” he said under cross-examination from Pistorius's lawyer Barry Roux.

Stipp said he felt for a pulse, but Steenkamp was beyond saving.

“To me it was obvious that she was dying. I noticed blood in her hair and brain tissue mingled with that.”

In the first four days of Pistorius's trial, the State has called four of his neighbours, who all testified that they heard loud voices coming from his house on the night of the shooting.

This appears to support the prosecution's argument - dismissed by Pistorius as “unfair and incorrect” - that the couple had a row before he shot Steenkamp.

Stipp said he heard somebody cry out in mortal fear, as did a married couple who took the stand earlier.

“The woman screamed like three or four times,” he said.

“She sounded to be emotional, anguished, scared, almost scared out of her mind, I would say.”

In relentless cross-examination of the witnesses, Roux has repeatedly made two claims that are emerging as the corner stones of the defence.

Firstly, he contends that they could not have heard Steenkamp scream because a head shot left her too severely brain damaged to make a sound.

“It was a terribly serious, devastating head wound.”

This drew an objection from state prosecutor Gerrie Nel, who said it could not be stated as fact that the first shot Pistorius fired killed Steenkamp, thus making it impossible for her to scream.

But Roux has insisted that what the witnesses heard, was in fact a shocked Pistorius scream for help in a high-pitched voice.

He told Stipp he would prove that the paralympian champion's voice rises when he is distraught.

“I put to you that it does. Decibel tests were done.”

Roux's second argument has been that witnesses mistook for gunfire the sound of a cricket bat striking wood as Pistorius broke down the toilet door into which he had fired his gun.

Pistorius, who is yet to take the stand, claims he shot through the door thinking there was an intruder inside.

His lawyer has hammered on the timing of the noise and two phone calls for help two minutes apart Ä one from Pistorius Ä and said anything heard in between could only have been the sound of the bat.

On Thursday morning, Roux accused another neighbour, Charl Johnson, of redrafting his written testimony several times to match his wife's recollection and incriminate Pistorius.

“That is what it's all about,” said Roux, theatrically waving a copy of Johnson's statement across the court room.

Johnson, who is Afrikaans, countered: “It's the nature of how I do my work ... I try to improve the quality of the work that I write... to use proper English and grammar.”

Afterwards, the prosecutor moved to defend Johnson's credibility.

Nel used his re-examination to show that though the witness learnt during Pistorius's bail hearing that there were only four shots, he had not changed his statement to reflect this, but kept to his original, more vague recollection.

Pistorius is also charged with illegal possession of a firearm and ammunition, and two counts of discharging a firearm in public.

The State on Wednesday called professional boxer Kevin Lerena to describe how Pistorius had made a friend take the blame after a gun went off in his hand in a packed restaurant a month before Steenkamp's death.

During Pistorius's bail hearing, Nel had honed in on this incident and suggested it showed Pistorius to be reluctant to take responsibility for his actions.

Nel also at the time dismissed a contention that Pistorius's distress on the night of the shooting showed he did not intend to kill Steenkamp.

Remorse could have kicked in immediately, he argued.