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LONDON (CNN) -- Oscar Pistorius was in a "loving and caring relationship" with Reeva Steenkamp, the girlfriend he is accused of murdering, the sprinter's agent testified Tuesday.
Pistorius involved his girlfriend in conversations about business and wanted her to travel with him so she could see what his life was life, Peet van Zyl said on the stand at the athlete's murder trial.
He was excited about taking her to a concert by Italian opera singer Andrea Bocelli, the agent said.
Van Zyl also described the sprinter as "hypervigilant" and "fidgety," saying Pistorius once grabbed his arm when they heard a bang on a street in New York, but he denied that the athlete was prone to outbursts of anger.
Van Zyl had lost his temper more often than Pistorius during the years they worked together, he said.
The double amputee sprinter is on trial for killing Steenkamp in February last year. He admits killing her, but says he mistook her for a burglar and thought he was defending himself.
The prosecution says the two had an argument and he killed her intentionally.
Van Zyl took the stand after an acoustics expert, Ivan Lin, was cross-examined about sounds on the night of killing.
Some neighbors have described hearing a woman's screams between shots the night Steenkamp died, but the defense has argued that Pistorius sounds "like a woman screaming" when he's anxious.
On the stand for the defense Monday, Lin said it would be "impossible" to replicate the "highly complex sound transmission" from Pistorius' house the night he killed Steenkamp.
He told court that "typically," one can differentiate between male and female screams, but not without exception.
Nel pressed him on the point but made little headway on Tuesday.
The prosecutor did get Lin to concede that state witnesses could have heard screaming from the Pistorius house on the night of the killing from their homes up to 177 meters (yards) away.
The trial restarted Monday after a month-long break when Pistorius was evaluated by mental health experts at the prosecution's request.
They found he was not mentally incapacitated when he shot Steenkamp to death.
According to the findings by an independent panel of doctors, Pistorius did not suffer from a mental defect or mental illness at the "time of the commission of the offense that would have rendered 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 Thokozile 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 at least 15 years in prison and possibly 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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