"I just don't feel that this is the right (verdict)," June Steenkamp told America's NBC News a little after Judge Thokozile Masipa found Pistorius not guilty of murder, but convicted him on a less serious charge of culpable homicide.
Steenkamp said her 29-year-old daughter had died a "horrible, painful, terrible death."
"And I can't believe that they believe that it was an accident," she said in her first reaction to the judgement.
The father of the model and law graduate also said he found it difficult to believe the court's ruling.
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"It was disbelief on everyone," said Barry Steenkamp in the same interview.
Asked what kind of sentence she would like to see imposed on Pistorius, the mother said: "I really don't care what happens to Oscar, it's not going to change anything because my daughter is not gonna come back.... She is gone forever."
Culpable homicide carries no mandatory sentence under South African law and a judge could decide on anything from a suspended sentence to several years behind bars.
The 27-year-old athlete -- whose journey from disabled infant to Olympic sprinter inspired the world -- will hear his punishment when sentencing begins on October 13.