Luigi Mangione's defense team intends to introduce psychiatric evidence in his New York state murder case involving the killing of UnitedHealthcare CEO Brian Thompson, a judge said this week.
Manhattan Supreme Court Justice Gregory Carro said Wednesday that Mangione's attorneys filed notice in September 2025 that they planned to present psychiatric evidence during trial proceedings. The defense has not publicly disclosed the specific mental health evidence it intends to introduce.
Prosecutors said they had not received details about the defense's psychiatric expert or the mental condition Mangione's attorneys plan to argue. Carro ordered the defense to provide additional information, saying prosecutors should not face a surprise shortly before trial.
Under New York law, Mangione's defense appears to be relying on an "extreme emotional disturbance" argument. Unlike a traditional insanity defense, the strategy requires the defense to show that the defendant experienced a qualifying mental state that affected responsibility for the alleged conduct.
If successful, the defense could lead to a not-guilty verdict or a reduction to a lesser charge, according to court proceedings.
The introduction of psychiatric evidence does not necessarily mean a defendant will be found not guilty because of mental illness. Courts typically examine whether a defendant's mental state met the legal standard and whether expert testimony supports a connection between that state and the alleged conduct.
Mangione faces separate state and federal prosecutions stemming from Thompson's death. The psychiatric defense announced this week applies to the New York state case. The federal case is proceeding separately, and it remains unclear whether the defense will pursue a similar strategy there.
Mangione is accused in the December 2024 shooting death of Thompson, who led UnitedHealthcare, one of the nation's largest health insurers. Mangione was arrested days later in Pennsylvania.
The case has drawn significant attention across the healthcare industry because of Thompson's role as a healthcare executive and the broader public discussion that followed the killing related to insurers.
Mangione's attorneys previously succeeded in having the top counts dismissed in both the state and federal cases, sparing him from a potential capital prosecution in the federal matter.
His state trial is expected to begin in September, with the federal case expected to follow.
The defense will now be required to provide additional details about its psychiatric evidence as both sides prepare for trial.
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