Prosecutors in South Africa will appeal Oscar Pistorius’ conviction for culpable homicide and his five-year sentence, a spokesman said via Twitter on Monday. The prosecution seeks a murder charge against Pistorius, who shot and killed his girlfriend, Reeva Steenkamp.

“The appeal on conviction is based on the question of law,” the statement read. “The merits and the demerits of the [National Prosecuting Authority] will become evidence when we file papers for leave to appeal.” The appeal should be filed “within the next few days,” according to the statement.

The Paralympian and Olympian shot and killed his girlfriend, Reeva Steenkamp, through the bathroom door on Valentine’s Day 2013. Pistorius claimed he thought Steenkamp was an intruder, but the prosecution contended that he was aware that he was firing at Steenkamp. Pistorius was convicted of culpable homicide last month and sentenced to five years in prison last Tuesday. The conviction is comparable to a manslaughter charge in the United States.

Judge Thokozile Masipa, who convicted Pistorius of culpable homicide, determined that he should have realized that his actions would end with someone’s death. Her sentencing statement indicated she sought to balance the need for justice and mercy.

“I am of the view that a non-custodial sentence would send a wrong message to the community,” she said. “On the other hand, a long sentence would not be appropriate either, as it would lack the element of mercy.”

The prosecution could argue that even if Pistorius thought Steenkamp was an intruder, he still knew that someone was behind the door, so knew that his actions could end up with a fatality, according to the Associated Press. Pistorius began serving his sentence immediately after the conviction. He is eligible to be released and serve out his sentence under house arrest after 10 months in prison. Arnold Pistorius, Oscar's uncle, said the family "accepted" the verdict.

The prosecution will file for a “leave of appeal,” which is made in the form of a legal argument that Judge Masipa will review, according to the Independent. She can grant the appeal if she determines that another judge could have come to a different conclusion than herself. The National Prosecuting Authority can go to the Supreme Court if she rejects the application.