Prosecutor Gerrie Nel told Oscar Pistorius to take public responsibility for hilling Reeva Steenkamp and challenged him to look at a graphic photo of her injuries.
Mr Nel started his cross examination of the Olympic athlete in the Pretoria High Court today in what proved to be one of the most intense days in the murder trial to date.
The court was shown a photo of Ms Steenkamp's head, showing a large amount of blood and human tissue. Mr Pistorius shot her four times through a closed toilet door at his home last year.
"It's time that you look at it," the prosecutor told Mr Pistorius sternly.
The double amputee responded: "I don't have to look at a picture. I was there."
Mr Pistorius went on to reveal that his hands had touched her brains when he attempted to stem the bleeding following the incident. He continued to refer to the killing on Ms Steenkamp "a mistake", which Mr Nel took exception to.
Mr Nel shouted: "You made a mistake? You killed a person, that's what you did! You used to be a model to disabled athletes everywhere.
"You shot and killed her, won't you take responsibility for that?"
Mr Pistorius replied: "I did."
Mr Nel continued to try to pick holes in the accused's story, attempting to depict him as a hothead with an obsession for shooting and killing.
The court was shown a video of Mr Pistorius firing a large weapon at a watermelon at a shooting range.
As the melon disintegrates, a male voice like that of Pistorius is heard saying: "It's a lot softer than brains. But (bleep) it's like a zombie stopper."
Mr Pistorius accepted that it was his voice, causing a stir as Paralympic champion had earlier denied knowing what a zombie stopper was.
He also described how Ms Steenkamp had passed away while he desperately tried to resuscitate her and held her as he waited for an ambulance.
Mr Pistorius was giving evidence for the third day and denies intentionally killing model Ms Steenkamp in the early hours of Valentine's Day last year.
The case continues.