Oscar Pistorius will be released from prison for good behavior on August 21 and go under house arrest after serving just 10 months for killing girlfriend Reeva Steenkamp, South Africa's department of corrections has said.

"He's behaving himself very well," Zach Modise, acting National Commissioner of Correctional Services, told AP news agency on Monday. "He hasn't given us any problems."

Yet three months after he leaves Kgosi Mampuru II prison in Pretoria, the double-amputee Olympic athlete will again face the possibility of a murder conviction and could be sent back to jail - this time for a minimum of 15 years.

Judge Thokozile Masipa had already granted prosecutors permission to go to the Supreme Court of Appeal, the second-highest court in South Africa, to appeal her decision to acquit Pistorius of murder at trial.

The appeal will now start sometime in November, Supreme Court registrar Paul Myburgh said on Monday.

Acquittal

Pistorius was acquitted of murder and found guilty of the lesser charge of culpable homicide, or manslaughter, last year for shooting Steenkamp through a toilet door in his home. Prosecutors will again seek a murder conviction at the Supreme Court of Appeal in November, the court announced, also on Monday.

Pistorius' impending release after serving one-sixth of his five-year jail term for manslaughter is in line with South African law. But it was sharply criticised by family members of Steenkamp, the 29-year-old model and reality TV star shot multiple times by Pistorius in the pre-dawn hours of February 14, 2013.

"Incarceration of 10 months for taking a life is simply not enough," Steenkamp's family said in a written statement to the parole board that met on Friday and approved Pistorius' release under correctional supervision, or house arrest.

Steenkamp's family members were invited to attend Pistorius' parole hearing, but did not. Instead, they sent the written submission, Tania Koen, Steenkamp family lawyer, said.

"We have forgiven Mr Pistorius even though he took the life of our precious daughter, Reeva," the family wrote in its submission. "We do not seek to avenge her death and we do not want Mr Pistorius to suffer; that will not bring her back to us. However, a person found guilty of a crime must be held accountable for their actions."

Source: AP