Prosecutors filed an appeal on Monday calling for Oscar Pistorius, who is days away from being released from prison, to be convicted of the murder of his girlfriend Reeva Steenkamp.

The Paralympian was jailed last year for five years after being convicted on the lesser charge of culpable homicide, the South African equivalent of manslaughter. He is set to be paroled on Friday after serving 10 months behind bars, but will remain under a form of house arrest.

He is expected to stay at his uncle Arnold’s three-storey mansion in a wealthy suburb of Pretoria. He is likely to be allowed to leave the house to work, carry out community service or to attend important family events, and officials say he will not have to wear an electronic monitoring device.

The state filed its heads of argument with the supreme court of appeal. Pistorius’s defence team has until 17 September to submit its response, with the appeal hearing expected in November. If the judges rule against Pistorius, he could face returning to prison for at least 15 years.

The double amputee, who became a sporting celebrity after competing in the Paralympics and Olympics, told his high profile trial that he mistook Steenkamp for an intruder when he fired four shots through a locked toilet door on Valentine’s Day in 2013.

The state is appealing against the culpable homicide verdict, arguing that Pistorius deliberately killed Steenkamp, a model and law graduate who would have turned 32 this Wednesday, after an argument. It has described his sentence as “shockingly inappropriate”.

Because of his physical disability, Pistorius has been held since 21 October in the hospital ward of Kgosi Mampuru II prison in Pretoria. He is eligible for release in line with guidelines that say non-dangerous prisoners should spend only a sixth of a custodial sentence behind bars.

The 28-year-old is to leave prison on Friday after the parole board agreed to place him under “correctional supervision”.

Steenkamp’s parents, Barry and June, have objected to Pistorius’s release. “Statistics show that our society is under continuous attack from criminals and murderers,” they wrote earlier this year. “Incarceration of 10 months for taking a life is simply not enough. We fear that this will not send out the proper message and serve as the deterrent it should.”