Warrant officer Hilton Botha also told the Pretoria magistrates court on Wednesday that Pistorius' girlfriend, model and law graduate Reeva Steenkamp, was hit by three bullets, in the head, elbow and hip.

Pistorius, a double amputee known as the "Blade Runner", broke down in tears as Botha presented his testimony.

The shooting has stunned South Africa and the millions around the world who saw the track glory of the athlete, who had no lower legs, as an inspiring tale of triumph over adversity.

Steenkamp was in a locked toilet adjoining Pistorius' bathroom when she was shot in the early hours of Thursday last week.

Botha said the angle at which the shots were fired through the door suggested the shooter had aimed specifically to hit somebody on the toilet.

Botha, who arrived at the scene at 4:15am local time (02:15 GMT) to find Steenkamp dead at the bottom of the stairs, also said police had found unlicensed .38 ammunition in Pistorius' house in an upmarket gated compound north of Pretoria.

Botha also said police found two containers of testosterone and needles in Pistorius' bedroom, as he said the athlete was a flight risk and should not be granted bail.

Nowhere to go

Prosecutors were preparing to outline on Wednesday why they believe the double-amputee Olympian murdered his model girlfriend.

Prosecutor Gerrie Nels  told the court on Tuesday  that he would elaborate on the state's version that Reeva Steenkamp and the athlete had a fight and that she fled to the toilet before Pistorius shot through the door four times and killed her.

"She couldn't go anywhere," Nels told the packed courtroom. "It must have been horrific."

Nel said Pistorius committed premeditated murder when he rose from his bed after a fight with Steenkamp, pulled on his prosthetic legs and walked about seven metres from his bedroom to the locked toilet door and pumped it with four bullets, three of which hit the model.

That contradicted the runner's statement, read aloud by defence lawyer Barry Roux, who described how the couple spent a quiet night together in the athlete's upscale home in a gated community in the capital of Pretoria, then went to sleep at about 10pm.

Sometime before dawn, Pistorius said he awoke, and walking only on his stumps, pulled a fan in from an open balcony and closed it.

That is when he said he heard a noise and became alarmed because the bathroom window, which had no security bars, was open and workers had left ladders nearby.

"It filled me with horror and fear," Pistorius said in the statement. "I am acutely aware of violent crime being committed by intruders entering homes," he said.

The magistrate has said that Pistorius' defence must offer "exceptional" reasons for him to be freed on bail.