Paralympian Oscar Pistorius' murder sentence more than doubled in new ruling The convicted killer of his girlfriend will now serve over 13 years in jail.

 -- Paralympic athlete and convicted killer Oscar Pistorius will spend the next 13 years and five months behind bars after the South African Supreme Court of Appeal (SCA) lengthened his jail sentence from six years to the maximum penalty.

The National Prosecuting Authority (NPA) turned to the SCA earlier this month to appeal the sentence handed down by the High Court in Pretoria.

The former paralympic gold medalist and Olympic competitor shot and killed his girlfriend model Reeva Steenkamp in the overnight hours of Valentine's Day in 2013.

Pistorius argued he shot Steenkamp, just 29 at the time of her death, through a bathroom door thinking she was an intruder.

The Supreme Court of Appeal said based on the evidence, it finds it difficult to believe that the man nicknamed the "Blade Runner" is genuinely remorseful about Steenkamp’s death. The SCA ordered that Pistorius receive the maximum possible sentence in this case of 15 years, however, it did take into account the time Pistorius has already served.

Steenkamp's family said they now feel they have "justice" for her with the doubled sentence.

"We felt that we didn't have justice for Reeva, by that's too lenient a sentence, but now we have justice for her," June Steenkamp, mother of Reeva Steenkamp, told Reuters.

"We just feel that now we can get on with our lives, that everything has come to an end, and I, right from the beginning, always said justice hadn't been served. Today it has," Reeva Steenkamp's father, Barry Steenkamp, added.

The double amputee’s brother, Carl Pistorius, said he was “shattered‚ heartbroken‚ gutted” by the Supreme Court of Appeal’s ruling in a post on Twitter Friday morning, shortly after the SCA handed down its judgment.

Oscar Pistorius, who turned 31 behind bars this week, could potentially be out of jail for his 40th birthday if he is granted parole, but Department of Correctional Services spokesperson Singabakho Nxumalo says it’s not a given that will happen.

“We will have to look at court papers and only once he has served the minimum of the total sentence, will he be considered [for parole],” Nxumalo said.

The disgraced athlete was originally convicted of culpable homicide -- similar to the U.S. judicial definition of manslaughter -- in the Pretoria High Court in 2014. However, the SCA upgraded his conviction to murder after the NPA appealed.

The matter was referred back to the court in Pretoria, which sentenced him to six years for the murder of Reeva Steenkamp. The NPA again turned to the Appeals Court, saying the sentence was "shockingly inappropriate."