Pistorius' uncle, Arnold Pistorius, told the Associated Press Saturday that his nephew is "numb with shock, as well as grief" over the shooting death of his girlfriend, model Reeva Steenkamp.
The 29-year-old model was shot four times Thursday at Pistorius' home in a gated community in South Africa's capital, Pretoria. A pistol was found at the house.
Police said Pistorius was at his home after the death of Steenkamp and "there is no other suspect involved."
Prosecutors said they plan to pursue a charge of premeditated murder against him. Arnold said the family "strongly refutes" any murder charge against the Olympic athlete.
"After consulting with legal representatives, we deeply regret the allegation of premeditated murder," Arnold Pistorius said. "We have no doubt there is no substance to the allegation and that the state's own case, including its own forensic evidence, strongly refutes any possibility of a premeditated murder or murder as such."
Several South African media outlets had initially reported that the shooting may have been accidental. But there will be a variety of hearings before Pistorius, 26, could go on trial.
In South Africa, there are no juries, so a judge ultimately would decide Pistorius' guilt or innocence, sometimes with the help of two advisers. At an initial hearing Friday, Pistorius sobbed and held his head in his hands at times. He has yet to enter a plea in the case. He is is in jail awaiting a bail hearing scheduled for Tuesday.
His uncle told the Associated Press that his nephew and Steenkamp had become very close since they started dating in November.
"They had plans together and Oscar was happier in his private life than he had been for a long time," the uncle said.
On Saturday, South Africa's state broadcaster SABC aired a reality TV show called "Tropika Island of Treasure" which features the model.
"I think the way that you go out, not just your journey in life, but the way that you go out and the way you make your exit is so important," Steenkamp said in the video. "You either made an impact in a positive or a negative way, but just maintain integrity and maintain class and just remain true to yourself."
The Associated Press contributed to this report.