Oscar Pistorius mental health analysis: Did diagnosis backfire on his defense team?

The murder trial of Oscar "Blade Runner" Pistorius entered a new phase that is now focusing on the former Olympic track star's mental health.

A judge ordered the double amputee to begin psychiatric testing next week, to learn his state of mind when he shot and killed his girlfriend, model Reeva Steenkamp. The order puts the trial on hold for more than a month.

The move was prompted by a defense witness, forensic psychiatrist Dr. Merryll Vorster, who diagnosed Pistorius with general anxiety disorder. CBS News legal analyst Rikki Klieman explained the defense did not pursue a full-blown insanity defense, but the prosecution grabbed onto the mental health angle.

"The prosecution said, 'Aha, well, maybe we should really have a psychiatric evaluation. And if so, if he really is mentally ill, mentally incapacitated, a Pistorius with a gun could be a dangerous Pistorius'," Klieman said.

The decision may have backfired on the defense.

"What happens if it winds up that he is truly mentally ill and he gets sentenced forever into a mental institution?" Klieman said.

The only potential "good news" for Pistorius, Klieman said, would be if they find he has diminished capacity, which could lessen his sentence.

Turning to the defense's case, Klieman said it's hard to say what they're looking to prove.

"Was it an accident? Was it a mistake? Or did he intend to do what he did because of this diminished capacity and he reacted differently because of a general anxiety disorder where his (instinct) is to fight?" Klieman said.

For more on the case, watch Klieman's full analysis above.