'Pitbull' prosecutor: Reeva doesn't have a life because of what you've done
*'You killed her. You shot and killed her. Won't you take responsibility for that?' prosecutor asks Pistorius
* 'Take responsibility for what you have done' prosecutor tells tearful Pistorius
* Gruesome pictures of dead Reeva Steenkamp shown to court
* Pistorius hides head in hands - says he takes responsibility 'but will not look'
* Pistorius asked about 'zombie stopper' video footage
* Sprinter said he knew Steenkamp was dead before medics arrived
A South African prosecutor forced Oscar Pistorius on Wednesday to look at a forensic photograph of the head of his girlfriend Reeva Steenkamp after it was destroyed by a gunshot fired by the Olympic and Paralympic track star.
In a dramatic opening to his cross-examination of Pistorius, prosecutor Gerrie Nel made him say that he had killed Steenkamp then later confronted him with the photograph showing the side and back of her skull matted with blood and brains.
"Take responsibility for what you have done," Nel said, drawing gasps from the public gallery and causing Pistorius to bury his head in his hands in the witness stand, rock from side to side and weep.
The double amputee sprinter, once revered across the world for his triumph over adversity, faces life in prison if convicted in the Pretoria High Court of the murder of Steenkamp, a 29-year-old law graduate and model.
His defence hinges on his contention that he though he was firing at an intruder when he shot Steenkamp through a toilet door in his luxury Pretoria home on February 14 - Valentine's Day - 2013.
Nel, renowned as one of South Africa's toughest state attorneys, sought to show the 27-year-old was a hot-headed character who loved to play with guns.
He asked Pistorius, well-known as a weapons enthusiast, if he knew what a "zombie stopper" was, to which the defendant answered no.
After a brief adjournment, the court then viewed video footage broadcast before the trial by Britain's Sky News of Pistorius firing a .50 calibre handgun at a watermelon at a shooting range.
As the melon disintegrates, Pistorius says off-camera: "It's a lot softer than brains. But (bleep) it's like a zombie stopper."
Nel then pushed the track star, saying he had shot the melon because he wanted to see what a bullet hitting a person's head looked like.
"You know that the same happened to Reeva's head. It exploded. I'm going to show you," he said, before projecting the forensic photograph of Steenkamp's head on the court monitors.
Steenkamp was hit by three of four hollow-point rounds fired by Pistorius through the toilet door. One hit her behind the right ear, killing her almost instantly, pathologists had earler told the court.
Pistorius acknowledged responsibility but said between sobs: "I will not look".
Television stations carrying the feed from the court apologised to viewers as the graphic image was broadcast live.
With no direct witnesses, Nel's main task is to pick holes in Pistorius' testimony and cast doubt on his statements about a perceived burglar.
He opened his questioning by asking Pistorius about his reputation as a global athletics star and strong Christian beliefs before hitting him with the reality of what took place.
"You are a model for sportsmen, disabled and abled bodied sportsmen, all over the world?" Nel asked.
"I think I was, My Lady. I made a mistake," replied Pistorius, answering to Judge Thokozile Masipa.
"You killed a person, that's what you did," came the reply.
"I made a mistake. My mistake was that I took Reeva's life," said Pistorius
"You killed her. You shot and killed her. Won't you take responsibility for that?" Nel said.
Earlier, Pistorius described his frantic attempts to revive Steenkamp after he found her lying on the toilet floor and how she had died in his arms, her blood pouring over his body.
"I checked to see if she was breathing and she wasn't," he said. "I could feel the blood was running down on me."
After several attempts, he managed to carry Steenkamp down stairs where neighbours tried to administer first aid before paramedics arrived.
But Pistorius said he knew that Steenkamp - with whom he said he was planning to buy a house - was already dead.
"Reeva, Reeva had already died whilst I was holding her, before the ambulance arrived, so I knew there was nothing they could do for her."