South Africa's Oscar Pistorius has been convicted of murder by South Africa’s Supreme Court, overturning the manslaughter conviction against the multiple Paralympic champion.
The Supreme Court upgraded the 29-year-old Paralympian's sentence on appeal to murder from 'culpable homicide', for which he had received a five-year sentence
"Guilty of murder, with the accused having criminal intent," Judge Eric Leach told the court.
"The matter is referred back to the trial court to consider an appropriate sentence."
Last year, Pistorius was convicted on a lesser crime of manslaughter, or culpable homicide, for shooting Steenkamp through a toilet door in his home early on Valentine’s Day 2013.
The athlete left jail on parole in October and was meant to serve the rest of his sentence under house arrest, but now after this fresh verdict he may go back to prison for up to 15 years.
"This is a human tragedy of Shakespearean proportions," Leach said as he started reading the ruling.
"A young man overcomes huge physical disabilities to reach Olympian heights as an athlete. In doing so he becomes an international celebrity, he meets a young woman of great natural beauty and a successful model, romance blossoms, and then, ironically on Valentine’s Day, all is destroyed when he takes her life."
Leach added that "as a matter of common sense, at the time the fatal shots were fired the possibility of the death of a person behind the door was clearly an obvious result."
State prosecutors who lodged the appeal say Pistorius intended to kill Steenkamp and that she fled to a toilet during a row. Pistorius denies deliberately killing Steenkamp, saying he mistook her for an intruder at his home.
Pistorius' lower legs were amputated when he was a baby but went on to become a global sporting hero.
Anneliese Burgess, the Pistorius family's spokeswoman, said the family would wait for lawyers advice on what to do next.
The athlete has been living with his uncle in a wealthy suburb in the capital Pretoria since being freed on parole.
Steenkamp's mother June, who has said she does not want retribution, attended the court session. She shed tears as she left the court after the new judgement was handed down.
The case has prompted a fierce debate in a country beset by high levels of violent crime. Some rights groups say the white track star - dubbed "Blade Runner" because of the carbon fibre prosthetic blades he uses to race - got preferential treatment.
At the original trial in September last year, Judge Masipa ruled that the state had failed to prove intent or ‘dolus eventualis’, a legal concept that centres on a person being held responsible for the foreseeable consequences of their actions.
Dolus eventualis refers to whether a person foresees the possibility that his or her action will cause death but carries on regardless.