South African Supreme Court judges hearing arguments from state lawyers that a high court judge had made legal errors when she decided not to convict "blade runner" Oscar Pistorius of murder, said they would issue their decision at a later date.
The Paralympic gold medallist was freed on parole last month after serving a fifth of the prison term given to him for the "culpable homicide" of Reeva Steenkamp, who he killed on Valentine's Day 2013.
Prosecutors said Pistorius should be convicted of murder and sent back to jail, while the defence argued that the sentence the athlete had received was appropriate and should stand.
Pistorius himself did not attend the one-day Supreme Court hearing into his highly-charged case, which has prompted a fierce debate in South Africa, and accusations from some rights groups that the white track star got preferential treatment.
Members of the ruling ANC party's Women's League at the session told reporters that Pistorius had been let out too soon and should get the minimum 15-year sentence for murder.
"We are here for Reeva’s family and the state," the League's Gautain province spokeswoman, Jacqui Mofokeng, said.
Prosecutors began their case arguing that a high court judge had made legal errors when she decided not to convict Pistorius of the more serious charge of murder last year.
The five Supreme Court judges could convict Pistorius of murder themselves, order a retrial or reject the prosecution's appeal, legal experts have said.
State lawyers said they would aim to show that the high court not only approached the circumstantial evidence incorrectly, but also incorrectly excluded relevant evidence.
"We have to convince the court that we are dealing with errors of law," chief state prosecutor Gerrie Nel said.
"The court ignored the most important circumstantial evidence that would make the respondent's version ... impossible."
Lead defence attorney Barry Roux said it was unfair to say that the court had ignored evidence.
Steenkamp's mother June, who last week said she did not want retribution, attended the session in Bloemfontein, 400 km (250 miles) southwest of Johannesburg, but did not make a statement.
Pistorius, dubbed ‘Blade Runner’ because of the carbon fibre prosthetic blades he uses to compete, denied deliberately killing his girlfriend, saying he mistook her for an intruder at his home.
Prosecutors said Pistorius intended to kill Steenkamp, who they said fled to a toilet during a row. Pistorius shot through the door four times, hitting her.
At the original trial in September last year, high court Judge Thokozile 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.
The athlete, whose lower legs were amputated when he was a baby, was freed two weeks ago in line with sentencing guidelines that say non-dangerous prisoners should spend only a sixth of a custodial sentence behind bars.
He has not been seen in public since then and is under house arrest that confines him to his uncle's home in a wealthy Pretoria suburb for the duration of his sentence.
South Africa has one of the world's highest rates of violent crime.