In a stunning reversal, Luigi Mangione’s legal team said on Thursday they would no longer pursue a psychiatric defense in his upcoming state trial over the killing of the UnitedHealthcare CEO Brian Thompson.

Just one day earlier, Mangione’s lawyers told Judge Gregory Carro they would pursue a defense claiming the 28-year-old was suffering an “extreme emotional disturbance” at the time of Thompson’s killing on 4 December 2024.

Mangione’s lawyers had faced a deadline on Thursday to provide prosecutors with information to support the emotional disturbance claim.

“They need to know the malady and how that triggered emotional disturbance,” Carro said during Wednesday’s hearing.

In a letter to Carro on Thursday, Mangione’s lawyer Karen Friedman Agnifilo said the defense “respectfully withdraws” its notice under New York’s psychiatric defense statute.

Mangione has pleaded not guilty to state and federal charges. His state trial is scheduled to start on 8 September. His federal trial, which involves stalking charges, is set to begin on 13 October.

If Mangione were to have gone through with the extreme emotional disturbance defense, he would have in effect been admitting that he killed Thompson but did so because of mitigating circumstances. It would not have absolved him of responsibility, but could have led to less time in prison.

If a jury accepts the defense, it is obligated to convict a defendant of manslaughter, which is punishable by up to 25 years in prison, instead of murder, which carries a potential life sentence.

Mangione’s lawyers did not immediately return a request for comment. The Manhattan district attorney’s office, which is prosecuting the state case, declined to comment.

Also on Thursday, a transcript of a secret hearing held on the matter on 3 June was made public after Carro ordered it unsealed.

At Wednesday’s hearing, Friedman Agnifilo protested against Carro’s decision to unseal materials related to his psychiatric defense, saying it would be “prejudicial to his defense to the exact same facts” in his federal case, where an extreme emotional disturbance defense is not allowed.

An emotional disturbance defense is not the same as a not guilty by reason of insanity defense, which would allow a defendant to go to a psychiatric facility instead of prison.

Thompson, 50, was killed as he walked to a Manhattan hotel for UnitedHealth Group’s annual investor conference. Surveillance video showed a masked gunman shooting him from behind. Police say “delay”, “deny” and “depose” were written on the ammunition, mimicking a phrase used to describe how insurers avoid paying claims.

Mangione, an Ivy League graduate from a wealthy Maryland family, was arrested five days later at a McDonald’s in Altoona, Pennsylvania, about 230 miles west of Manhattan.

At a hearing last month, Carro ruled that a gun and notebook that prosecutors say link Mangione to the killing can be used as evidence against him.

The gun, a 3D-printed pistol, matches the one used to kill Thompson, prosecutors said. The notebook describes wanting to “wack” a health insurance executive and rebelling against “the deadly, greed fueled health insurance cartel”.

The Associated Press contributed reporting