The murder trial of South African Olympic sprinter Oscar Pistorius continues in the North Gauteng High Court on Wednesday. Dr Stipp, a radiologist and formerly of the military, testified on the fourth day of the trial. He was the first person on the scene after the shooting, having woken to the sound of "three loud bangs".

Thinking they were gunshots, he got out of bed and went to his balcony, when he heard what he thought was a female screaming three or four times.

When he got to Mr Pistorius' house, he found the athlete kneeling by Ms Steenkamp, with "his left hand on her right groin, and his right hand - the second and third fingers - in her mouth".

"I shot her," the Paralympic star told him. "I thought she was a burglar."

"He was crying, he was praying, he was talking to God, he was telling God to let her live, please don't let her die," Dr Stipp told the Pretoria High Court. Dr Stipp also testified that he saw a bathroom light on at Mr Pistorius's house and a figure moving from right to left as a woman screamed.

The double amputee denies intentionally killing her, saying he mistook the 29-year-old model for an intruder. If found guilty, Mr. Pistorius could face life imprisonment.

Pistorius' defense team, led by Barry Roux, alleges that Pistorius fired the four shots at his girlfriend through a locked bathroom door in a tragic case of mistaken identity. It says he heard a noise in the bathroom, grabbed his 9 .mm pistol and without putting on his prosthetics, made his way to the locked door. They claim he fired thinking he was protecting himself and Steenkamp from an intruder. His team also states that the couple had not argued that evening.

Earlier, defence lawyer Barry Roux said that two neighbours, Michell Burger and Charl Johnson, had discussed their testimony with each other and amended the rough notes they had made a few days after the shooting.

Johnson told the court that on the night of the killing, he heard a woman scream, a man yell for help and then gunshots.

"I can confidently say I heard gunshots," Johnson insisted on cross-examination by Roux on the fourth day of Pistorius' murder trial. Later, Johnson said: "I'm convinced that I heard a lady's voice screaming for help, followed by a man."

Roux argues that prosecution witnesses Johnson and his wife are mistaken over what they heard on the night Pistorius killed his girlfriend. Roux says the banging sounds were actually Pistorius hitting a toilet door with a cricket bat and the screaming was the distressed athlete calling for help.

In the early morning hours of February 14, 2013 (Valentine's Day), Pistorius, 27, fired four shots, the last one a fatal blow to the head of his girlfriend, Reeva Steenkamp, 29.

Pistorius, known as the Blade Runner, competed at the 2012 Olympics on specially designed prosthetic legs. He is the first double-amputee to compete at an Olympics, running in both the 400 meters and the 4x400 meter relay races.