Pretoria, South Africa (CNN) -- Oscar Pistorius prosecutor Gerrie Nel wants the South African track star sent for independent psychiatric evaluation, he said Monday, in a move that could delay the athlete's murder trial for a month or more. 

A psychiatrist testified Monday that Pistorius has an anxiety disorder stemming from his double amputation as an infant and his unstable parents. 

He's depressed now and feeling guilt from having killed his girlfriend, Reeva Steenkamp, defense witness Dr. Meryl Vorster said on the stand. 

Nel responded by comparing the athlete's mental state to post-traumatic stress disorder and saying the law required psychiatric observation. 

The prosecutor's extremely unusual move is essentially an effort to maneuver the court into considering an insanity or "capacity" defense even though the athlete's legal team is not mounting one, CNN legal analyst Kelly Phelps said. Phelps, a criminologist and law lecturer at the University of Cape Town, said she had never seen this done before. 

Pistorius' lead defense lawyer, Barry Roux, is fighting back, saying Nel is oversimplifying the law. 

The question was left unresolved when court adjourned for the day. Nel is due to submit his application on Tuesday after both sides have finished questioning Vorster. 

The psychiatrist took the stand Monday morning for the defense, going all the way back to when the disabled sprinter was 11 months old. 

Pistorius would have experienced the amputation of both of his legs below the knee at that time as a "traumatic assault" because he was too young to speak or understand what was happening to him, she said in court. 
For how long?
delay the athlete's murder trial for a month or more