JOHANNESBURG — Oscar Pistorius again faces the possibility of a murder conviction after a South African judge ruled Wednesday that prosecutors can appeal against the double-amputee Olympian’s conviction on the lesser charge of culpable homicide. The sensational case will go to the Supreme Court of Appeal, which will review the murder trial of Pistorius, who fatally shot girlfriend Reeva Steenkamp through the closed door of a toilet cubicle on Valentine’s Day last year. Judge Thokozile Masipa, who convicted Pistorius and sentenced him to five years in jail, acknowledged that chief prosecutor Gerrie Nel had raised legitimate “questions of law” that should be studied by the appeals court. “This might have a practical effect” on the conviction, Masipa said. “We note the finding of the court and abide by the ruling,” Pistorius’ family said in a statement. Pistorius could face a minimum of 15 years in prison if the appeals court overturns the culpable homicide conviction and raises it to a murder conviction. Under his current sentence, Pistorius could be released from prison and placed under house arrest after serving 10 months, or one-sixth of his sentence.