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PRETORIA, South Africa (CNN) -- Do not be taken in by the fact that Oscar Pistorius is one of the fastest runners in the world -- remember he is disabled, one of his doctors argued at the sprinter's murder trial Thursday.
Wayne Derman ran through a long list of the difficulties double amputees experience every day, concluding: "The saddest thing I have learned through my six years of working with athletes with disability is that disability never sleeps.
"It's there when you go to sleep at night and it's there when you wake up in the morning. It affects nearly every aspect of your life," he said.
Pistorius's defense team seems to be trying to establish that he acted reasonably, given who he is, on the night he killed his girlfriend Reeva Steenkamp in his home last year.
He is on trial for murder, and while he admits firing the bullets that killed her, he pleaded not guilty, saying he mistakenly thought he was defending himself from an intruder.
The prosecution says the two had an argument and he killed her intentionally.
Judge Thokozile Masipa must decide whether he made a genuine mistake, and, if so, whether the mistake and his response were reasonable.
The South African Olympian's defense team has been exploring his psychology this week.
His lawyer Kenny Oldwadge posited Thursday that there were "two Oscars," one of whom was a global sports star and one of whom was "vulnerable" and "scared."
"I am stuffed without my legs on," his lawyer quoted him as saying, using a slang term meaning "in trouble."
On Wednesday, another of his lawyers said Pistorius is depressed, suffering from post-traumatic stress disorder, and is a suicide risk, according to the doctors who spent a month evaluating his mental health.
But he does not appear to have a history of abnormal aggression or psychopathic tendencies linked to "rage-type murders in intimate relations," they found.
The conclusions, read by lead defense lawyer Barry Roux, are a "slam-dunk for the defense," CNN legal expert Kelly Phelps said.
The psychiatric report seemed to suggest that Pistorius's version of events was plausible.
"When Mr. Pistorius's appraisal of the situation is that he might be physically threatened, a fear response follows that might seem extraordinary when viewed from the perspective of a normal bodied person, but normal in the context of a disabled person with his history," the doctors found.
Several witnesses have testified that Pistorius tends to arm himself and go towards danger, rather than away from it, when he thinks he is under threat.
The trial restarted Monday after a monthlong break when Pistorius was evaluated by mental health experts at the prosecution's request.
They found he was not mentally incapacitated when he shot and killed Steenkamp.
An independent panel of doctors said that Pistorius was, at the time he shot Steenkamp, not mentally ill or incapacitated in any way that would make him "criminally not responsible of the offenses charged."
The report added that "Mr. Pistorius was capable of appreciating the wrongfulness of his act."
Had the doctors deemed Pistorius mentally incapacitated during the shooting, the trial would have immediately ended in a verdict of not guilty by reason of mental illness.
At the trial's conclusion, Judge Masipa will have to decide whether Pistorius genuinely made a mistake or killed Steenkamp intentionally.
If she does not believe the athlete thought there was an intruder, she will find him guilty of murder and sentence him to a prison term ranging from 15 years to life. South Africa does not have the death penalty.
If Masipa accepts that Pistorius did not know Steenkamp was the person he was shooting at, she could find him guilty of culpable homicide, a lesser charge than murder, or acquit him, according to CNN legal analyst Kelly Phelps.
A verdict of culpable homicide would leave the sentence at Masipa's discretion.
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