Mangione’s lawyers informed Judge Gregory Carro on Thursday that they would no longer seek an extreme emotional disturbance defense in the Dec. 4, 2024 shooting of Thompson in Manhattan. The decision came ahead of a deadline requiring the defense to provide prosecutors with supporting information for the claim.

In a letter to the court, defense attorney Karen Friedman Agnifilo said the defense “respectfully withdraws” its notice under New York’s psychiatric defense statute “at this time.”

The move marked a sharp reversal from Wednesday’s court hearing, when Mangione’s legal team said they intended to argue that he was suffering from extreme emotional disturbance when Thompson was killed. Under New York law, such a defense does not absolve a defendant of criminal responsibility but can reduce a murder conviction to manslaughter if accepted by a jury.

A manslaughter conviction in New York carries a sentence of up to 25 years in prison, while a murder conviction can result in a life sentence.

Following the defense’s withdrawal, Carro rescinded an order that would have unsealed transcripts and materials from a closed June 3 hearing related to the psychiatric-defense issue. However, copies of the transcript had already been provided to some media organizations before the judge’s latest ruling.

According to court proceedings, the transcript contained no additional details regarding the basis for the proposed emotional disturbance claim.

Mangione has pleaded not guilty to both state and federal charges stemming from Thompson’s killing. His state murder trial is scheduled to begin on Sept. 8, while a separate federal trial involving stalking-related charges is set for Oct. 13.

At Wednesday’s hearing, Agnifilo argued against making materials related to the psychiatric-defense strategy public, saying disclosure could prejudice Mangione’s defense in the federal case, where an extreme emotional disturbance defense is not available.

The emotional disturbance defense differs from a not guilty by reason of insanity plea, which can result in psychiatric treatment rather than imprisonment if successful.

Thompson, 50, was shot and killed while walking to a Manhattan hotel where UnitedHealth Group was holding its annual investor conference. Surveillance footage showed a masked gunman shooting him from behind, according to prosecutors.

Investigators have said the words “delay,” “deny” and “depose” were written on ammunition recovered in the case, echoing language often used by critics of health-insurance claims practices.

Mangione, an Ivy League graduate from a prominent Maryland family, was arrested five days after the shooting at a McDonald’s restaurant in Altoona, Pennsylvania.

In a ruling issued last month, Carro allowed prosecutors to use a 3D-printed handgun and a notebook allegedly recovered from Mangione as evidence at trial. Prosecutors contend the firearm matches the weapon used in the shooting and that notebook entries referenced a desire to target a health-insurance executive and oppose what was described as a “deadly, greed fueled health insurance cartel.”