Johannesburg: The prosecution in Oscar Pistorius’s murder trial asked the court to order the athlete to undergo mental observation after a forensic psychiatrist diagnosed an anxiety disorder that may have affected his actions when he killed Reeva Steenkamp.

Prosecutor Gerrie Nel requested the judge in the high court in Pretoria, South Africa’s capital, to send Pistorius for 30 days of observation after defense witness Merryll Vorster said the Paralympic athlete suffered from general anxiety disorder. Defense lawyer Barry Roux opposed the application.

On the accused’s version, there is an indication that psychiatric disorder may have played a role, Nel said on Tuesday. The fact that it is a psychiatric diagnosis may play a role and must play a role and that’s what we base our application on.

Double-amputee Pistorius, 27, says he thought Steenkamp, his model girlfriend, was a burglar when he fired four shots through a locked toilet cubicle door in his bathroom at his home on Valentine’s Day last year. The prosecution says he killed Steenkamp in a fit of rage.

Nel also questioned why the defense asked Vorster to evaluate Pistorius this month, weeks after he testified in a trial that started 3 March. The prosecutor suggested it may be part of the defense’s fall back position.

Judge Thokozile Masipa will give her ruling on the application on Wednesday.

Shutting door

By requesting the assessment, Nel probably expects Pistorius to be declared mentally capable and may be seeking to shut the door on a possible appeal on the basis of mental illness, James Grant, associate professor of criminal law at the Johannesburg-based University of the Witwatersrand, said by phone.

It’s also a strategic move to force the defense to clarify what exactly their defense is, he said. From the moment of their plea explanation it does seem to have shifted slightly to language that might be putting capacity for self control in question.

The runner appeared to change his argument from self- defense when he testified last month, saying that he fired the gun by accident and didn’t mean to pull the trigger.

Vorster, a forensic psychiatrist at the University of the Witwatersrand, said Pistorius is depressed and that his grief is genuine.

Anxiety disorder

While the athlete knew the difference between right and wrong, she said, it may be his ability to act in accordance with such appreciation was affected by this generalized anxiety disorder.

Asked by Nel on Monday if an armed person with such an anxiety disorder is a danger to society, Vorster said: Yes.

Sufferers of the disorder probably shouldn’t have guns, she said in her testimony today.

People generally with general anxiety disorders probably shouldn’t have firearms, Vorster said. While general anxiety disorder is not associated with violence, she said, when you add a firearm it makes that person a risk.

Vorster’s testimony came as Roux started the final push of the defense’s bid to undermine the prosecution’s case that Pistorius shot Steenkamp after an argument, portraying the athlete as being paranoid about crime.

‘Improbable’ version

Since the prosecution described Pistorius’s testimony last month as untruthful and improbable, Roux has called witnesses who cast doubt on the state’s version of the shooting and tried to show the runner as being emotionally distraught after the shooting.

Nel has portrayed Pistorius as a short-tempered gun-lover who shot Steenkamp in a fit of anger. Pistorius only became emotional during his testimony when he was asked difficult questions, Nel argued.

Masipa, who will give the final judgment in the case because South Africa doesn’t have a jury system, could consider a lesser charge of culpable homicide if she rules that the act wasn’t intentional. Pistorius would face a minimum of 25 years in jail if convicted of murder. He’s also pleaded not guilty to three separate gun-related charges.

Known as the Blade Runner because of his J-shaped prosthetic running blades, Pistorius has been free on 1 million rand ($96,000) bail since February last year.

The charges have derailed the running career of the winner of six Paralympic gold medals and cost Pistorius sponsorship deals with Nike Inc, Luxottica Group SpA’s Oakley and Ossur hf, the Icelandic company that manufacturers the blades he uses.

Pistorius was the first double amputee to compete at the Olympic Games in London in 2012. BLOOMBERG