JOHANNESBURG —South Africa’s highest court has dismissed Oscar Pistorius’ appeal of his murder conviction, a lawyer said Thursday, signaling that the former track star’s long legal battle since he killed girlfriend Reeva Steenkamp may be drawing to a close.

The ruling by the Constitutional Court clears the way for a judge to sentence the double-amputee runner for murder at a hearing scheduled for April 18.

Pistorius, who killed Steenkamp in 2013, had appealed to the Constitutional Court, saying another court erred when it overturned a manslaughter conviction and declared the Olympic athlete guilty of murder.

Pistorius spent one year of a five-year sentence in jail for the lesser offense. He is currently under house arrest, staying at his uncle’s mansion in Pretoria.