Luigi Mangione, who is charged with the killing of UnitedHealthcare chief executive Brian Thompson, is set to present a psychiatric defence in his state murder trial.

The lawyers have told Judge Gregory Carro that Mangione was suffering from extreme emotional disturbance at the time the shooting took place, a factor that could reduce a murder conviction to manslaughter if the jury accepts the claim.

Judge Carro will make court records related to this defence strategy public. The state trial is scheduled to open on September 8.

Malign accusations have also applied to Mangione for federal stalking charges, which, if convicted, could pull up a life sentence. Earlier this year, federal murder and firearms accusations were dropped.

The incident occurred on December 4 outside a Manhattan hotel where Thompson had entered a conference. Mangione is an Ivy League graduate who came from a wealthy Maryland family.

Luigi Mangione in the courtroom