Oscar Pistorius was an "appalling witness" who repeatedly lied in his testimony in a crude attempt to defend himself against a murder charge over killing his girlfriend, the chief prosecutor at his trial has said.
During closing arguments, Gerrie Nel also harshly criticised the legal team of the double-amputee, saying it floated more than one theory about what happened on the night he shot Reeva Steenkamp through a closed toilet door in his home.
He said defence lawyers had argued that Pistorius acted in self-defence, fearing an intruder was in the house, but also raised the possibility that he was not criminally responsible, accidentally shooting Ms Steenkamp because he was "startled".
"It's two defences that you can never reconcile," Mr Nel said as Pistorius sat behind him in the dock. The once-celebrated athlete appeared calm, in contrast to some past occasions during which he retched and wailed in apparent distress.
The fathers of the Olympic runner and Ms Steenkamp, a model and television personality, were in the Pretoria courthouse for the first time since the trial began in early March.
They sat at opposite ends of a long bench in the gallery. Pistorius is said to be estranged from his father, Henke, and Ms Steenkamp's father, Barry, has been ill.
Pistorius' older brother Carl, who has regularly attended court sessions, is in an intensive care unit in a South African hospital and was on a ventilator because of injuries suffered in a serious car crash last week, the Pistorius family said.
Barry Roux, the chief defence lawyer, listened and checked files as Mr Nel spoke for hours, occasionally urged by Judge Thokozile Masipa to speed up.
He elaborated on the prosecution's written arguments of more than 100 pages that were submitted to the court last week. Mr Roux will present his final arguments on Friday before Judge Masipa adjourns the trial to deliberate with two legal assistants on a verdict.
The prosecution has argued that Pistorius intentionally shot Ms Steenkamp before dawn on February 14 last year after a quarrel. The defence has contended that he fired by mistake, thinking he was about to be attacked by an assailant in the toilet and that she was in the bedroom.
Pistorius was vague in allegations that police had possibly tampered with evidence around the scene of the shooting, including fans and a bed cover strewn on the floor of his bedroom, according to Mr Nel.
It was also improbable that the athlete, in his version, rushed with his gun to investigate a purported sound in the bathroom without first trying to talk to Ms Steenkamp and confirm that she was safe, the prosecutor said.
"We cannot argue that he was the worst witness ever, that honour belongs to someone else," said the prosecution's written argument. "The accused was, however, demonstrably one of the worst witnesses ever encountered."
The prosecution said Pistorius "used well-calculated and rehearsed emotional outbursts to deflect the attention and avoid having to answer questions".
A psychologist who examined Pistorius during a court-ordered observation period concluded he had become severely traumatised since the killing and could become an increasing suicide risk unless he continues to get mental health care.
In addition to the murder charge, Pistorius faces three separate gun-related charges, one of which stems from his alleged firing of a shot in a crowded restaurant in Johannesburg, months before he killed Ms Steenkamp. He has pleaded not guilty to all charges.
Because South Africa has no trial by jury, Judge Masipa will decide whether Pistorius committed murder, is guilty of a negligent killing, or if he made a tragic error and should be acquitted.
The runner faces 25 years to life in prison if convicted of premeditated murder, and would also be sent to prison for years if found guilty of murder without premeditation or culpable homicide.
Earlier, Judge Masipa told Mr Nel and Mr Roux that they had only until the end of Friday to complete their final arguments in court.
"Unless, of course, you want to work on a Saturday and perhaps Sunday, after church," she said, smiling.
The prosecution argues Pistorius knew Ms Steenkamp was in the bathroom.
Mr Nel ended his closing argument by saying he was guilty of premeditated murder because he then "made up his mind" to find his gun, walk through to the bathroom and shoot.
"That, my lady, is pre-planning," he said to the judge.
Mr Nel said Pistorius should still be convicted of murder even if the court accepts he did not know it was Ms Steenkamp in the toilet cubicle.
He argued the athlete intentionally shot at and killed a person with no reason to believe his life was under threat.
Mr Roux began his final arguments before Judge Masipa postponed proceedings until tomorrow for the defence to finish.
He noted that some of the evidence at the scene, which Mr Nel referred to, had been moved around by investigators.
"We're not talking about a conspiracy," Mr Roux said, calling it unintentional.
He also noted that Hilton Botha, the former chief investigating officer in the case, had acknowledged mistakes in police procedure but was not called by the state as a trial witness.