South African state prosecutors on Tuesday argued in court for Oscar Pistorius to be convicted of murder and sent back to jail, two weeks after he was released on house arrest. The disgraced Paralympic sprinter was found guilty last year of culpable homicide — a charge equivalent to manslaughter — after shooting dead his girlfriend Reeva Steenkamp on Valentine's Day in 2013. At the Supreme Court of Appeal in Bloemfontein, state prosecutors tried to convince judges that Pistorius should be found guilty of murder and sentenced to a minimum of 15 years in prison. He was released on Oct. 19 — just one year into his five-year jail term — to spend the remainder of his sentence at his uncle's mansion in Pretoria. Pistorius, 28, said he thought there was an intruder in his house when he blasted four bullets through the toilet door of his bedroom, killing Steenkamp, a model and law graduate. Prosecutor Gerrie Nel began his case, arguing that Pistorius intentionally meant to kill whoever was behind the door. The state lawyers have described the sentence as "shockingly light, inappropriate" and said "not enough emphasis was placed on the horrendous manner" in which Steenkamp died. A panel of five judges will hear the arguments from the state and defense, with the proceedings scheduled to last one day. The judges are then expected to announce a future date to deliver their ruling. "I'm here to support Gerrie Nel and the team," said Reeva's mother June Steenkamp said, sitting in court. "We are saying he must stay in jail," said Khosi Mojapi, a 33-year-old member of the African National Congress Women's League, outside the court building. "As women, we need to make sure the law is behind us. We say stop abusing women." A lone Pistorius supporter held a sign reading "Hands off Oscar Pistorius, Give Oscar Pistorius a break." "We need to ensure everybody gets a second chance at life," said Tokelo Africa, wearing a white fedora and navy suit. Pistorius, who has not been seen in public since his release, did not attend the hearing. Legal experts said it was difficult to predict the outcome of the appeal given the unexpected — and sometimes unprecedented — legal twists and turns that have characterized the case. "The possibilities are to dismiss the appeal, uphold the appeal, or refer it back to the trial court — which I think is very unlikely — for resentencing or retrial," criminal lawyer Martin Hood said. If the judges uphold the state's appeal and find Pistorius guilty of murder, he could have just 48 hours to prepare for a return to prison. Pistorius may also make his own appeal to South Africa's Constitutional Court — the country's highest court. But defense lawyer Barry Roux previously said Pistorius could not afford further legal battles, having already paid huge legal bills. Pistorius shot his girlfriend at the peak of his fame, following his historic performance in 2012 when he became the first double-amputee to race at Olympic level. In the shooting's aftermath, he lost his glittering sports career, lucrative contracts and status as a global role model for the disabled. His release on house arrest after serving one-sixth of his sentence was in line with normal treatment of South African convicts, but was criticized by women's rights groups and many others in the country. When Pistorius was due for release in August, the justice minister intervened to insist on a delay, in a move the athlete's legal team claimed smacked of political interference. Steenkamp's family have said they may wish to meet with Pistorius to help them cope with her death.