The verdict, pronounced by Judge Thokozile Matilda Masipa, was the culmination of a closely watched drama that transfixed many around the world after Mr. Pistorius shot and killed his girlfriend, Reeva Steenkamp, 29, in the early hours of Valentine’s Day last year, saying he believed an intruder had entered his home.
Wielding a handgun loaded with hollow-point ammunition, he opened fire on a locked toilet cubicle door only to discover when he broke the door down with a cricket bat that Ms. Steenkamp was inside. The prosecution sought to prove that he intended to kill her, but he called her death an accident and a mistake.
Judge Masipa asked Mr. Pistorius, 27, to stand in the wooden dock in the North Gauteng High Court here in the South African capital as she pronounced her verdict. The athlete, dressed in a dark suit, white shirt and black tie, looked straight ahead, his hands crossed in front of him, seemingly impassive after several instances during the trial when he wept, wailed and retched.
In the hushed courtroom, with members of both the Steenkamp and the Pistorius families looking on, the judge told Mr. Pistorius that he had acted negligently when he opened fire.
The prosecution, she said, had failed to bring “strong circumstantial evidence” to support its case of murder, while Mr. Pistorius’s version of events “could reasonably be true.”
After the shooting, Mr. Pistorius had been prompt in calling for help, the judge said. He prayed to God and sought to resuscitate Ms. Steenkamp, a model and law-school graduate, and his behavior, the judge said, “was inconsistent” with that of someone who wanted to commit murder.
Moreover, she said, “it cannot be said that the accused did not entertain a genuine belief that there was an intruder in the house.” He could thus not be found guilty on murder charges, Judge Masipa said.
But, she said, Mr. Pistorius had been negligent when he opened fire, knowing that somebody might be inside the toilet cubicle.
“A reasonable person with a similar disability would have foreseen the possibility that the person behind the door” would have been killed, the judge said.
Mr. Pistorius was born without fibula bones and both legs were amputated below the knee at age 11 months, leaving him to compete on scythe-like prostheses that inspired the nickname Blade Runner, after the movie. As an athlete, fighting adversity and competing against able-bodied as well as disabled athletes, Mr. Pistorius became an emblem of South Africa’s self-image as a land that punches above its weight. But the killing stripped the sheen off what had been a glittery story of success and celebrity.
The judge also acquitted Mr. Pistorius of two firearms charges and convicted him of another. Judge Masipa said state prosecutors had “failed to establish that the accused is guilty” of firing a pistol through the sunroof of a car and “must be acquitted.” She also acquitted him of a charge of illegal possession of ammunition. On a count relating to a shot fired in a crowded restaurant, she found Mr. Pistorius guilty.
The verdicts represented a crushing blow for the lead prosecutor, Gerrie Nel, who had demanded that Mr. Pistorius be convicted of premeditated murder, an offense that carries a mandatory minimum jail term of 25 years.
Judge Masipa did not immediately pronounce a sentence. Culpable homicide, which relates to negligence rather than intent, can draw a 15-year term, but the judge has wide discretion in determining the punishment. Either side can appeal the case to a higher court, and the National Prosecuting Authority said it would decide whether to do so after sentencing.
After the verdict, Mr. Pistorius’s lawyer, Barry Roux, asked for Mr. Pistorius to remain free on bail, as he has been for most of the 18 months since the killing, living in the luxurious home of a wealthy uncle. “I think it is premature to think of a likely sentence in this case,” Mr. Roux said. “There is no reason not to allow him out on bail.”
Mr. Nel, the prosecutor, disagreed and called for the athlete to be taken into custody following his conviction. “This is a very serious case that makes a lengthy sentence possible,” Mr. Nel said, alluding to a potential risk of suicide. “I do not think it is in the interests of justice” for him to be released on bail, the prosecutor said.
When the court adjourned to allow Judge Masipa to deliberate on whether Mr. Pistorius should be granted bail, bailiffs led him to a holding cell.
The trial began in March and had initially been set to last three weeks, but it was frequently delayed, most dramatically by weeks of psychiatric tests which established that the runner was mentally fit to stand trial.
The case, broadcast around the world and compared in its global fascination to the O. J. Simpson trial in the United States, has touched on far broader issues in this still divided society, 20 years after the democratic elections that formally ended the harsh racial segregation called apartheid. South Africa still struggles with race, violence and crime — factors that have not been lost on Judge Masipa, who grew up in the hardscrabble township of Soweto and struggled against the racial odds to qualify as a lawyer.
The judge acknowledged Thursday that Mr. Pistorius was particularly afraid of crime. But in a land where millions face danger without the gated residential complexes, security guards — and highly paid legal teams — of the rich elite, she was careful to note that his fears did not excuse his actions. “Many people in this country have experienced crime,” she said, “but they have not resorted to sleeping with a firearm under their pillow.”