Oscar Pistorius, a South African paralympian who was found guilty for shooting to death his then girlfriend in 2013 has filed papers to appeal his 13-year- sentence to the constitutional court.

The South African supreme court of appeal had in November increased his jail sentence to 13-years and 5 months in prison for murder of Reeva Steenkamp.

According to reports, Pistorius was supposed to be sentenced to 15-years in prison but the court minimized it to 13-years after taking into account the time he had already served in prison before the court`s judgment.

The State had applied to have Pistorius’s initial six-year prison sentence increased.

The world-renowned athlete was arrested on Valentine’s Day in 2013 – the day of the killing.

He fired four shots through a bathroom door, claiming that he believed there was an intruder in the bathroom.

North Gauteng High Court Judge Thokozile Masipa initially sentenced Pistorius to five years for culpable homicide in 2014.

Pistorius served only 10 months of the five-year sentence in prison before being released and put under house arrest.

The State appealed the culpable homicide conviction, and it was later replaced with murder by the Supreme Court of Appeal in 2016.

The State petitioned the SCA directly, arguing that the six-year sentence was far too lenient.