In an unexpected move, prosecutors in the Oscar Pistorius murder trial argued on Monday that the Olympic medalist suffers from anxiety, which was a contributing factor when he shot and killed his girlfriend in February 2013.

On Monday, prosecutor Gerrie Nel stated that the South African track star should be sent for an independent, psychiatric evaluation, CNN reported. If granted, Pistorius' murder trial could be delayed for more than a month.

A psychiatrist also took the stand to testify that Pistorius has an anxiety disorder that was caused by his double amputation as a baby and growing up in an unstable home.  Defense witness Dr. Meryl Vorster added that he's depressed and feels guilty about killing his girlfriend, Reeva Steenkamp, on Valentine's Day.

Nel also told the court that the athlete's mental state is comparable to post-traumatic stress disorder, which the law requires psychiatric observation.

"It is my opinion, my lady, that Mr. Pistorius has an anxiety disorder. If he was afraid that there was an intruder, then certainly having a generalised anxiety disorder would have affected the way he reacted to that fear," said Nel, according to The Guardian.

Pistorius, the first amputee athlete in the Olympics, lost both of his legs when he was 11 months old. On February 14, 2013, he claims that he mistook Steenkamp for an intruder when he shot her in his home.

Forensic psychiatrist Meryll Vorster said that the reaction of Pistorius to an intruder would have been different to that of a "normal, able-bodied person without generalised anxiety disorder."

However, she aruged that this would not have affected his ability to distinguish between right and wrong. Therefore, it was up to the court to decide whether his anxiety disorder should relieve him of responsibility in the shooting.

"I think the generalized anxiety is relevant to the case. But the court will have to decide," she said.

When Nel asked Vorster whether a gun owner is "a danger to society," she replied saying, "Yes."