Luigi Mangione Withdraws His Emotional Disturbance Defense For Now

4:37 PM PT -- Sources with knowledge tell TMZ ... Luigi's lawyers will resurrect the Extreme Emotional Distress defense as they get closer to the trial date. We're told the reason they backed off now is that they are doing more psych evaluations with Luigi and don’t want to turn over the records until they are complete. They also don’t want to play their hand until they get closer to trial.

It's a shocker for sure ... Luigi Mangione has backed off his core defense that was just announced in court yesterday, but there may be more to this story than meets the eye.

As we reported, the judge in his New York State murder trial revealed Wednesday ... Luigi's lawyers were mounting a novel defense called Extreme Emotional Disturbance. Short story -- it essentially means he was out of his head when he shot and killed United Healthcare CEO Brian Thompson.

TMZ has reported extensively on Mangione's obsession with corporate greed ... and the defense planned to argue that obsession created an altered state in which Luigi felt he fired the gun to save humanity. If the jury bought the argument, it would reduce the murder charge to manslaughter.

Well, the defense just said it would not pursue the psychiatric defense.

Yeah, it's more than puzzling, but this could also be a legal maneuver. Today is the deadline for the defense to turn over to prosecutors records of Mangione's psychiatric history.

We're just guessing, but it could be that the defense team didn't want to give prosecutors a heads-up just yet on Luigi's medical records, so they put the emotional disturbance defense on ice for now, but may try to revive it later ... closer to trial.

The trial is set for early September.