Prosecutors in South Africa returned to court on Tuesday seeking a murder conviction for Oscar Pistorius in the shooting death of his girlfriend Reeva Steenkamp.

The Paralympian was convicted of culpable homicide, the equivalent to manslaughter, last year for the model’s death. However, prosecutors were not satisfied with that ruling and chose to appeal.

"On the objective facts, the accused cannot escape the conviction of murder," prosecutor Gerrie Nel said, addressing a panel of five judges in South Africa's Supreme Court of Appeal.

Pistorius’ lawyer, Barry Roux also presented arguments to counter Nel.

The Daily Star claimed that Roux may not have been very confident in his argument though and was overheard muttering, "I am going to lose."

Roux has not yet responded to the outlet’s claim.

Pistorius, who is a double-amputee and competed against able-bodied athletes in the 2012 Olympic Games in London, admitted that he shot Steenkamp through a closed bathroom door on Valentine’s Day 2013. However, while the prosecution has always called it murder, he has always said he mistakenly fired the shots believing she was an intruder.

As we reported, the athlete was released from prison last month after serving 11 months and is currently on house arrest.