Prosecutors have sought a murder conviction against Oscar Pistorius before South Africa’s Supreme Court of Appeal.
They claim a lower court erred in acquitting the double-amputee athlete of that charge for killing his girlfriend Reeva Steenkamp, instead convicting him of culpable homicide.
A panel of five judges could also rule that his manslaughter conviction should stand, or even order another trial.
If convicted of murder, Pistorius would face a minimum sentence of 15 years in prison.
South Africa no longer has the death penalty.
Prosecutors say Judge Thokozile Masipa made an error at Pistorius’s trial last year when she acquitted him of murder for killing Ms Steenkamp on Valentine’s Day 2013. On being found guilty of culpable homicide, he was sentenced to five years in prison.
Pistorius (28) was released from jail last month after serving a year in prison and was moved to house arrest at his uncle’s mansion. He was not present at the hearing.
June Steenkamp, Ms Steenkamp’s mother, was inside the courtroom. She sat behind chief prosecutor Gerrie Nel as he presented his arguments.
Asking the judges to upgrade Pistorius’s conviction to murder, Mr Nel said Judge Masipa did not correctly apply the law at Pistorius’s trial.
The prosecution’s argument rests on a part of South African law known as “dolus eventualis”, which calls for a person to be convicted of murder with lesser intent if they foresaw that someone could be killed as a result of their actions, but went ahead anyway.
Prosecutors believe Pistorius knew someone could die when he shot four times through a toilet cubicle door in the pre-dawn hours of February 14, 2013, killing Ms Steenkamp.
Pistorius gave evidence that he had no intention to kill and fired out of fear for his life, believing a dangerous intruder was inside the toilet cubicle.
Mr Nel also said Judge Masipa ignored or simply paid “lip service” to some circumstantial evidence against Pistorius at his trial.