A South African court has ruled that former Olympic and Paralympic athlete Oscar Pistorius is guilty of the murder of his girlfriend, Reeva Steenkamp, who was shot dead in Pistorius's home in Pretoria on 14 February 2013. The athlete said he took his gun and fired four bullets at the bathroom door fearing burglars had broken into his house. However, Steenkamp was found dead behind the door.

Justice Eric Leach read the verdict on behalf of a five-judge-panel at the Bloemfontein Supreme Court. He described the case as "a human tragedy of Shakespearean proportions" and said that the previous ruling – in which Pistorius was charged with manslaughter – was fundamentally flawed. It could not be disputed that Pistorius had shot Steenkamp who, he said, had nowhere to hide in the toilet. Leach said the defendant had changed his account of what happened several times and never offered an acceptable explanation.

He then discussed the concept of dolus eventualis, a legal principle at the core of this appeal case. Dolus eventualis outlines the situation in which people persist in their actions even if they are aware they can cause the death of someone. According to South African law, someone can be charged with murder if there is the intent in the form of dolus eventualis.

Leach said that in the previous trial, the court had misdirected itself on the dolus eventualis and the issue was to understand whether Pistorius could foresee that there was a person behind the door who could die. He said: "I have no doubt ... the accused must have foreseen and therefore did foresee that whoever was behind that door might die.The identity of his victim is irrelevant to his guilt."

Pistorius was found guilty of culpable homicide by judge Thokozile Masipa during the first trial at the Pretoria High Court. He was sentenced to five years in prison and was released on probation after 10 months, with Steenkamp's mother arguing the sentence was too short.

During an appeal hearing on 3 November, in which prosecutors tried to change the manslaughter sentence to murder, Pistorius's lawyer was accidentally heard saying he was going to lose.

Pistorius will be referred back to Judge Masipa for the murder sentence. Meanwhile, he will remain under house arrest at his uncle's home in Pretoria. A date for the hearing has not been set yet.