Luigi Mangione will argue a psychiatric defense in state murder trial

New York (CNN) — Luigi Mangione’s attorneys will present a psychiatric defense at his state murder trial this fall, arguing he killed UnitedHealthcare chief executive Brian Thompson while suffering an extreme emotional disturbance.

At a hearing Wednesday, Judge Gregory Carro said he planned to unseal records related to an affirmative defense available to New York state criminal defendants charged with murder, in which the accused admits to the charged conduct but argues they should not be held fully criminally liable because he or she acted while experiencing a mental health episode.

Experts have told CNN a psychiatric defense would be challenging but is likely Mangione’s best argument given the strength of the evidence against him. In a key ruling last month, Carro cleared the way for prosecutors to present crucial evidence they contend ties him to crime scene and could shed light on his motive for the killing.

A hearing in Mangione’s case earlier this month had been sealed at the defense’s request. The judge said he sealed information related to the psychiatric defense because it would have been “very prejudicial” to Mangione if his attorneys decided not to move forward with the strategy.

In court Wednesday, Assistant District Attorney Joel Seidemann accused the defense team of stonewalling the prosecution by not sharing information related to the extreme emotional disturbance, or EED, defense.

Carro ordered Mangione’s defense team to turn over information – including the name of their psychiatric expert and the basis of the argument – no later than Thursday.

“(Prosecutors) need to know what the malady is that this defendant suffers and how that triggered an extreme emotional disturbance at the time and place of the occurrence,” he said. “Nothing is going to be a surprise. I’m not going to let you surprise the People on the eve of the trial. So, get it done.”

The judge said further delay could preclude Mangione from using the defense at his state trial, which is slated to begin in September.

Mangione has pleaded not guilty to state murder and weapons charges in the December 2024 fatal shooting of Thompson as he walked toward a Midtown Manhattan hotel hosting his company’s annual investor’s conference.

On Wednesday, Carro also granted the prosecution’s motion to drop a weapons count from the case. The charge stemmed from a loaded magazine found in Mangione’s backpack when he was arrested in Pennsylvania, days after Thompson’s killing.

In May, the judge ruled the magazine, along with a handful of other items in Mangione’s bag, were inadmissible after finding police improperly searched his bag when they first encountered him at a McDonald’s in Altoona.

Mangione also has pleaded not guilty to federal stalking charges.

Lawyers previously told CNN typical defenses may be unavailable to Mangione because of the apparent strength of the physical evidence: Last month, Carro ruled to allow prosecutors to present the alleged murder weapon found in Mangione’s backpack and writings in which he purportedly expressed animosity toward the healthcare industry and a desire to “wack (sic) the CEO.”

Under the EED defense, a defendant charged with murder admits to the killing but argues they were acting under the influence of an extreme emotional disturbance spurred by an event that made them temporarily lose control, legal experts said.

If a jury finds a defendant has proved by a preponderance of evidence he acted because of an extreme emotional disturbance, the crime is reduced from murder to manslaughter, which carries far less prison time. If the jury convicts him of the lesser charge of manslaughter, he would face a maximum of 25 years, compared to the maximum sentence of life in prison he could face for a murder conviction.

Such a defense is often used in cases where a defendant acts in the heat of the moment, such as finding their spouse cheating on them. It can also be put forward in cases where a person acts upon emotions that have been festering for a long time, such as abused women who kill their attackers.

Some defendants, however, have successfully applied an EED defense in cases that differ from these typical scenarios – including when the defendant was found to be acting under the influence of drugs or acted based upon a mistaken belief.

This story has been updated with additional information.

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