Judge Thokozile Masipa will hear from both sides before making her decision. She ruled on September 12 that he was not guilty of murder, which would have carried a mandatory life sentence.
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She found him guilty of culpable homicide – roughly equivalent to manslaughter. The lesser charge had no minimum sentence, meaning that he could receive a suspended sentence or be set free. However, it is thought more likely that the athlete will be be given from five to ten years in prison.
The first witness was Oscar's psychologist Dr Lore Hartzenberg who testified that various experts had diagnosed Oscar with Post Traumatic Stress Disorder following the shooting.
Oscar Pistorius consults with a member of his defence team
She described him as "very emotional" during their sessions, adding that he wept continually during their sessions.
He was, she said, extremely distressed about not being able to contact Reeva's parents. After being rebuked on attempting to speak to them, her patient felt he was "damned if he did and damned if he didn't".
Dr Hartzenberg said that even although he appeared to lose his temper occasionally in court, he never did so in counseling sessions with her.
She went on: "I have never found him to be anything other than a respectful, caring and well-mannered person."
Dr Hartzenberg finished by saying : "We are left with a broken man who has lost everything."
As she spoke Reeva's mother June, who was accompanied by her husband Barry Steenkamp, shook her head. In his cross examination, prosecution lawyer Gerrie Nel asked the psychologist: "If Pistorius is a broken man, are the Steenkamps not a broken family?"
He also asked if the issue of the Paralympian returning to his athletics career ever came up during their session – which Dr Hartzenberg denied.
If he is jailed, the champion sprinter could be detained in Pretoria Central, Baviaanspoort, or the rural Zonderwater prison.