The question may linger forever: Did Oscar Pistorius know he was shooting at his girlfriend?

CAPE TOWN: In the decade since Oscar Pistorius pulled the trigger four times on his 9mm pistol, firing into the head and body of girlfriend Reeva Steenkamp as she stood inside a locked toilet cubicle in his home, the vital question has still never been answered: Did the world-famous Olympic runner know he was shooting at and killing his girlfriend that Valentine's Day in 2013?

Pistorius has always claimed that he didn't, that he mistook her for an intruder in his home. Steenkamp's family believes he intended to shoot the 29-year-old model and law graduate after becoming enraged in a nighttime argument.

Only Pistorius really knows for sure what he did, and he may be the only person who ever will.

The lasting twist of Pistorius' case, which shocked and riveted millions and was back in the spotlight Friday (Nov 24) when he was granted parole, is that even his conviction for murder didn't provide an answer to the lingering question.

Pistorius' parole comes 10 years after the killing. He will be released from prison on Jan 5, but will be constantly monitored by officials until his full 13-year, five-month sentence for murder ends in December 2029, the Department of Corrections said. Pistorius, who turned 37 this week, will have served just under nine years in prison when he’s let out. Serious offenders in South Africa must serve at least half their sentence to be eligible for parole.

Pistorius, who had his lower legs amputated as a baby but became a champion athlete, was ultimately found guilty of murder in Steenkamp's shooting on a principle of law called dolus eventualis. It means he knew the person - whoever it was - would likely be killed when he shot through that door in a bathroom in his Pretoria villa and went ahead anyway.