Oscar Pistorius was found guilty of murder on Thursday after South Africa`s Supreme Court of Appeal threw out a manslaughter conviction for killing his girlfriend, and he now faces a 15-year prison term.
The judge described the Paralympian`s testimony over the 2013 shooting of Reeva Steenkamp as "untruthful" and delivered a damning indictment of the original verdict.
The double-amputee athlete known as the "Blade Runner" was released on parole in October after serving one year of his five-year prison sentence for the lesser charge of culpable homicide.
He killed Steenkamp, a model and law graduate, in the early hours of Valentine`s Day two years ago, saying he mistook her for an intruder when he shot four times through the locked door of his bedroom toilet.
"Guilty of murder, with the accused having criminal intent," judge Eric Leach told the court in South Africa`s judicial capital Bloemfontein in a dramatic legal reversal.
"The matter is referred back to the trial court to consider an appropriate sentence."
The Paralympic gold medallist, who was not present in court, now faces a minimum 15-year sentence for murder -- although he could be released earlier on parole.
"It is inconceivable that a rational person thought he was entitled to fire at this person with a heavy-duty firearm," said Leach, who described Pistorius`s testimony as "vacillating and untruthful".
"He ought to have been convicted not of culpable homicide... but of culpable murder," the judge added.
The National Prosecuting Authority confirmed that Pistorius, 29, will remain on parole under house arrest at his uncle`s mansion in the capital Pretoria until he is re-sentenced.
"I`m satisfied with everything," Reeva`s father Barry Steenkamp told reporters shortly after the unanimous ruling by five appeal court judges.
Her mother June sat quietly in court with a sombre expression as the ruling was announced, and made no immediate comment afterwards.At the crux of the case was how trial judge Thokozile Masipa interpreted the principle of "dolus eventualis" -- awareness of the likely outcome of an action -- under which she acquitted Pistorius of murder.
"This was expected. Judge Masipa legally got the whole issue completely wrong," William Booth, a defence lawyer based in Cape Town, told AFP.
"Four shots into a tiny toilet when you know somebody is on the other side -- that person shooting knows he is going to hit the person.
"He faces a minimum of 15 years. My feeling is that he`s done a year, so looking at all the factors, maybe nine, 10 years in prison."
The trial of Pistorius, who became a global icon as the first double amputee to compete at the Olympics in 2012, attracted worldwide attention.
He denied killing Steenkamp, 29, in a rage after the couple had gone to bed, sobbing and occasionally vomiting in the dock as details of his lover`s death were examined in excruciating detail.
"I was overcome with fear," he said during his trial last year, describing how he thought he heard an intruder in the bathroom.
He grabbed his gun, and rushed without his prostheses to the bathroom.
"Before I knew it, I`d fired four shots at the door," he said, adding that he ran back to the bed only to find that Steenkamp was not there.
Pistorius killed Steenkamp at the peak of his fame, and he has since lost his glittering sports career, lucrative contracts and status as a global role model for the disabled.
Last month he made his first appearance in public since leaving jail, looking gaunt when he reported for community service at a Pretoria police station."The legal team will study the finding and we will be guided by them in terms of options going forward," a Pistorius family spokeswoman said in a brief statement.
Pistorius`s current parole conditions have not been made public, but are reported to require him to meet with Steenkamp`s parents if they wish.
He may make his own appeal to the Constitutional Court -- the country`s highest court.
"There is a very good chance that this might be appealed," said Kelly Phelps, University of Cape Town senior law lecturer.
"It would involve principles like the right to a fair trial (and) the correct ambit and jurisdiction of the Supreme Court of Appeal.
But Pistorius`s lawyers have said the sprinter cannot afford further legal battles, having already paid huge bills.
The case triggered fierce debate in South Africa about violence against women, and activists from the ruling ANC party`s women`s league packed the public benches throughout the long case.
"I`m overwhelmed. The women of South Africa, the women of the whole world, have won today," league spokeswoman Mapaseka Nkoane said outside the court.