Oscar Pistorius's 'split personality' led him to shoot his girlfriend, says expert, as he is torn between being an Olympic athlete and a disabled man

Oscar Pistorius’ natural response to the intruder he believed had broken into his home the night he killed girlfriend Reeva Steenkamp would be to fire his gun, rather than flee, according to an expert.

Speaking for the defence on day 37 of the Paralympian’s murder trial in Pretoria, Wayne Derman, a professor of sport and exercise at the University of Cape Town, said that for Oscar Pistorius ‘to flee is not an option because the individual does not have lower legs’.

Derman added that Pistorius is a 'paradox' whose racing triumphs contrast sharply with the severe limitations of his disability.

He said the contrast likely contributed to stress and anxiety for Pistorius.

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'Fight, not flee': Oscar Pistorius has no option to escape in the face of danger because of his disability, an expert at the Paralympian's murder trial said

Distracted: Pistorius uses a phone as he sits in the dock

Professor Derman, who has treated Pistorius, told the trial on Thursday that thinking stops when 'flight or fight' kicks in, and that his patient is always more likely to fight, because of his ‘significant disability’.

Pistorius maintains that when he fired his gun through the bathroom door of his home on February 14, 2013, killing Steenkamp, he thought he was shooting an intruder.

He previously told the trial: ‘I was not thinking - I just fired.’

Professor Derman told the court he found Pistorius to be 'hyper-vigilant' and was restless, often looking around quickly and scanning for possible threats.

'He is an anxious individual,' Derman said.

He also noted that Pistorius has a hand tremor as well as a sleep disorder that required medication.

The defense wants to show that the athlete had a deep sense of vulnerability and it was a factor in the 'mistaken shooting'. 

Chief prosecutor Gerrie Nel during cross-examination argued that Derman's testimony is likely to be biased because as a physician he is obligated to 'act in the best interests of his patients'.

Derman countered that he has backed up all his points with scientific facts.

'The truth would come before my patient,' Derman said.

Nel said: 'You cannot give evidence against your patient, sir.'

He suggested on Thursday that Pistorius acted methodically on the night he killed Steenkamp because he had to locate his gun, which was not where he normally kept it, then take the weapon out of its holster and then move down a passage from the bedroom to the bathroom while scanning for the perceived threat.

'The accused was careful before he entered the passage,' Nel said.

The trial heard earlier that Oscar Pistorius does not display the narcissism associated with men in abusive relationships and linked to 'rage-type' murders, according to a psychologist's report.

The report adds to conflicting evidence about the character of the double-amputee runner.

Defense says Pistorius suffers from depression

Preparation: Oscar Pistorius has his tie adjusted by his uncle Arnold Pistorius, right, in court during his ongoing murder trial in Pretoria on Thursday

Kenny Oldwage, one of the defence lawyers of South African paralympian Oscar Pistorius, gestures as he speaks during his client's murder trial at the High Court in Pretoria

The defense has sought to support Pistorius' contention that he killed the 29-year-old model by mistake, fearing an intruder was about to attack him; the prosecution says the Paralympian is a jealous egotist who shot Steenkamp after a Valentine's Day argument.

Dr. Jonathan Scholtz, a clinical psychologist, found no evidence that Pistorius had a history of 'abnormal aggression or explosive violence' but concluded he has a record of feeling insecure and vulnerable, particularly when he is without his prosthetic limbs, defense lawyer Barry Roux said. He read excerpts from the psychological report, part of a court-ordered evaluation of Pistorius' state of mind over 30 days at a state psychiatric hospital.

The evaluation, which included a separate report by three psychiatrists, said Pistorius was not mentally ill when he killed Steenkamp.

That conclusion appeared to remove the possibility that Pistorius could be declared not guilty by reason of mental illness. On Wednesday, his defense team tried to show that the psychologist's report supports the Paralympian's account of a mistaken shooting because his disability and purported fear of crime contributed to a heightened sense of vulnerability.

Trial: A supporter hugs Oscar Pistorius on Wednesday at the court in Pretoria

When physically threatened, Pistorius might have a fearful reaction that could 'seem extraordinary when viewed from the perspective of an able-bodied person, but normal in the context of a disabled person with his history,' said Roux, quoting from the report. The lawyer also cited the psychologist as saying Pistorius has become severely traumatized since the killing and will become an increasing suicide risk unless he continues to get mental health care.

At times during his trial, Pistorius has wailed and retched in apparent distress, particularly during graphic testimony about the shooting and also when the athlete was on the witness stand. At other times, he has been calm and taken notes. Nel has suggested Pistorius feigned distress in order to dodge a tough cross-examination; the athlete's camp has denied his emotional displays were fake.

Nel has portrayed Pistorius as a reckless narcissist with a penchant for gunplay and driving at high speeds. He has highlighted arguments between the runner and Steenkamp in the weeks before he killed her, though the defense has said most of their communication was normal and affectionate.

Pistorius, who is free on bail, faces 25 years to life in prison if found guilty of premeditated murder, but he could also be sentenced to a shorter prison term if convicted of murder without premeditation or negligent killing. Additionally, he faces separate gun-related charges.

DM