Carl Pistorius is charged with culpable homicide in the death of a motorcyclist in 2008; the case is unrelated to the Valentine's Day shooting of his younger brother's girlfriend.
However, it was not widely known of until local television e-News Channel Africa reported it on Sunday. A family statement said Carl appeared before a judge on Thursday and would be in court again in late March. His younger brother was freed on bail on Friday after a week of hearings watched by the world's media.
Carl Pistorius declined comment as he entered the home of an uncle in Pretoria on Sunday. The house is where Oscar, 26, has been staying since being granted bail on Friday until his trial for the premeditated murder of model Reeva Steenkamp on Feb. 14.
The family statement quoted lawyer Kenny Oldwage as saying:
"There is no doubt that Carl is innocent and the charge will be challenged in court. Carl deeply regrets the accident.
"Blood tests conducted by the police at the time proved that he had not been under the influence of alcohol, confirming that it was a tragic road accident after the deceased collided with Carl's car."
Contacted by Reuters, Oldwage declined further comment. The family statement said charges had at one stage been withdrawn but then reinstated.
Carl Pistorius attracted little publicity until the arrest of his younger brother propelled the family into the glare of a global media spotlight. He and their younger sister Aimee and father Henke, appeared in court to support Oscar, who denies the charge, saying he believed he was shooting at an intruder.
The younger Pistorius brother was born lacking bones in his lower legs, leading to amputation and carbon fibre blades. As the Paralympian "Blade Runner", who competed with able-bodied athletes at last year's London Olympics, reaching the semifinal of the 400 metres, he became a symbol of triumph over adversity.
In his native South Africa, he has also been seen as a rare hero for both blacks and whites, transcending racial divides that persist 19 years after the end of apartheid.
The trial has drawn attention to South Africa's judicial system. Defence counsel criticised police witnesses during the bail hearings and, in a development that prompted further headlines, the lead detective was replaced after it emerged he himself was facing attempted murder charges.
On Saturday, Steenkamp's father said that if Oscar Pistorius was telling the truth about mistakenly opening fire then "maybe I can forgive him one day". But he added that if the track star were lying "he will have to live with his conscience".