Oscar Pistorius, the double-amputee sprinter who rose to worldwide fame for overcoming his disability to compete in the 2012 Olympic Games, was sentenced on Wednesday to six years in prison for murdering his girlfriend, Reeva Steenkamp, inside his home in 2013.
Mr. Pistorius was taken directly from the courtroom to a prison near Pretoria to start serving his sentence. He will have to serve half of his term before being eligible for parole.
Judge Thokozile Matilda Masipa of the High Court in Pretoria cited “mitigating” factors in handing out a sentence that was significantly shorter than the 15-year minimum requested by prosecutors.
Mr. Pistorius, the judge said, had shown genuine remorse in trying, repeatedly and unsuccessfully, to apologize in person to the victim’s parents.
Mr. Pistorius, 29, who looked down in an expressionless stare while the judge read the sentence, showed no emotion when he was asked to rise and listen to the sentencing. Neither did Ms. Steenkamp’s family react in the courtroom.
The sentencing brought to an apparent close a trial that transfixed much of this nation for years, featuring a young, handsome man whose inspiring story once spoke to the youthful hopes of post-apartheid South Africa.
Mr. Pistorius’s fall — as well as the unsettling questions the trial raised about violence against women and the racial fears lurking behind the murder — occurred in a country increasingly disaffected with the post-apartheid order and its architect, the long-governing African National Congress.
In handing out the six-year sentence, Judge Masipa surprised many legal experts who had predicted that a term of at least 10 years would split the difference between guidelines that call for at least 15 years in prison for murder but that also allow for a reduction based on other considerations.
Both sides can appeal the judge’s sentence, leaving the possibility that the case may not be over. Mr. Pistorius’s lawyers said they would not file an appeal.
Perhaps anticipating a challenge by prosecutors, Judge Masipa said in her ruling Wednesday morning that she would be available to receive a request for an appeal that same day.
Among other mitigating factors, the judge said she considered the circumstances of the shooting and Mr. Pistorius’s disability.
She also noted that Mr. Pistorius was a first-time offender who had shown himself to be a good candidate for rehabilitation. “I am of the view that a long-term imprisonment will not serve justice,” Judge Masipa said.
In remarks largely sympathetic to Mr. Pistorius, the judge added: “He’s a fallen hero who has lost his career and is ruined financially. The worst is that having taken the life of a fellow human being in the manner that he did, he cannot be at peace.”
Marius du Toit, a criminal defense lawyer, former prosecutor and judge who has closely followed the trial, said the sentence, though “erring on the side of leniency,” clearly reflected the judge’s belief that Mr. Pistorius was guilty of what amounts to an accidental murder, not one with intent.
Mr. du Toit said that prosecutors could decide to contest the sentence by asking Judge Masipa to grant leave to appeal or, failing that, by petitioning the Supreme Court of Appeals directly.
“But is it something that another court will interfere with? I somehow don’t think so,” he said. “I think we may have reached the end of this matter.”
Gareth Newham, a criminal justice researcher at the Institute for Security Studies in Pretoria, said that it was not unusual for a judge to consider mitigating factors in deviating from sentencing guidelines. But the six-year sentence, he said, would most likely anger a public that has come to regard Mr. Pistorius much less sympathetically.
“The general public feeling about this will be that it was an inappropriately light sentence, and that could lead to the N.P.A. to think that they might have a better chance of getting the sentence extended if they took it to a higher court,” he said, referring to the National Prosecuting Authority.
After prosecutors appealed, the nation’s highest appeals court found that Judge Masipa had erred in her ruling and convicted Mr. Pistorius of murder.
Last month, Mr. Pistorius and Ms. Steenkamp’s family appeared in court before Judge Masipa for a new sentencing. Both sides made emotional pleas to the judge who, though working under sentencing guidelines, had the authority to reduce the sentence if she found substantial and compelling reasons.
In the courtroom last month, Mr. Pistorius removed his artificial legs and walked on his stumps, resting his hand on a desk for support at one point. His lawyers argued that his disability would make him particularly vulnerable in prison and pleaded for community service instead.
The victim’s father, Barry Steenkamp, 73, gave tearful testimony and said that Mr. Pistorius “had to pay for his crime.” Mr. Steenkamp said his daughter’s killing had contributed to his having a stroke.
Mr. Steenkamp, a diabetic, said that his grief has been so severe that he would take his insulin syringe and “shove it into my stomach and my arms to see if I could feel the same type of pain, but no.”
Ms. Steenkamp’s murder occurred only months after the 2012 Games, where Mr. Pistorius, a source of inspiration around the world for the disabled, was selected to carry the South African flag at the closing ceremony.
Mr. Pistorius, whose lower legs were amputated when he was 11 months old, became known as the Blade Runner for his use of curved prosthetics.
Mr. Pistorius and Ms. Steenkamp — a 29-year-old model and law school graduate — had been dating for only a few months when the killing took place, on Feb. 14, 2013.
That night, Mr. Pistorius shot Ms. Steenkamp through the locked door of a bathroom in his apartment in a gated community in Pretoria.
Mr. Pistorius had said that he had shot his girlfriend in the mistaken belief that somebody had broken into his home, an argument that resonated in a country with high crime — and high walls to shield the comfortable against home invasions.
Prosecutors argued that he had intentionally killed Ms. Steenkamp in a jealous rage after an argument.
In her initial verdict in 2014, after a five-month courtroom drama that many compared to the O.J. Simpson trial, Judge Masipa sided with the defendant, saying his account “could reasonably be true.”
Acquitting him of murder, she ruled that prosecutors had failed to prove beyond a reasonable doubt that Mr. Pistorius had shown intent to kill.
But as is permitted in South Africa, which does not have a jury system, prosecutors appealed to the Supreme Court of Appeal.
In December, the appeals court sided with prosecutors, concluding that the manslaughter conviction, called culpable homicide in South Africa, had been based on a misinterpretation of laws and an erroneous dismissal of circumstantial evidence.
The court said that, under a legal principle called dolus eventualis, Mr. Pistorius was guilty because he should have foreseen that his actions — firing through his locked bathroom door — would kill whoever was inside, and yet he proceeded regardless of the consequences.
In describing the case as “a human tragedy of Shakespearean proportions,” the appeals court overturned Judge Masipa’s conviction and found Mr. Pistorius guilty of murder.
Mr. Pistorius’s lawyers tried to take the case to the nation’s highest court, the Constitutional Court. But in March, the body, which usually handles constitutional matters, declined to hear Mr. Pistorius’s appeal.