Luigi Mangione’s Manhattan state court case in the killing of UnitedHealthcare executive Brian Thompson spiraled into legal chaos last week, spurring speculation about defense strategy for his upcoming murder trial.

The most prominent element of this uncertainty is defense lawyers’ potential backtracking over whether to pursue a psychiatric defense.

The eyebrow-raising series of events kicked off Tuesday with a measure of absurdist mundanity. Mangione – arguably the highest-profile criminal defendant in the US at present – missed court due to a simple paperwork error.

Judge Gregory Carro, who is overseeing this case, rescheduled Mangione’s much-anticipated court appearance for Wednesday. All things Mangione draw extensive attention, but this court date was of particular interest: Carro on 3 June had held a sealed proceeding at the defense’s request and had said he would address the secrecy at last week’s proceeding.

Mangione faces state and federal charges in the 4 December 2024 shooting of Thompson on a midtown Manhattan street. He has pleaded not guilty in both cases. Thompson’s slaying not only spawned a sprawling manhunt but renewed attention on Americans’ disdain for the for-profit US healthcare system.

On Wednesday, it became clear why Mangione’s defense would want to keep things under wraps.

Carro announced he would be “unsealing the record” relating to Mangione’s 250.10 notice – which is a defense declaration that “he was proceeding with an affirmative psychiatric defense … extreme emotional disturbance [EED] at the time and place of the occurrence”.

“You need to share the information, any records that your expert has relied on, what the defendant’s malady is, his mental defect that he suffers, all of that is to be turned over. Obviously, any report that an expert does, on both sides, must be turned over to each other,” Carro told the lawyers. This also meant that transcripts from the cloak-and-dagger proceeding would be released, with redaction.

As Carro indicated, transcripts from earlier this month were unsealed on Thursday, revealing that both sides discussed the defense’s interest in potentially pursuing an extreme emotional disturbance strategy.

In arguing for sealing, Mangione’s lawyer Karen Friedman Agnifilo said: “As you know, your honor, if a defendant goes with an EED defense, they’re essentially admitting publicly that they committed this crime.”

This information, in turn, can harm his state and federal cases because would-be jurors could see Mangione’s effective admission, she argued.

Then came another twist and what seemed like a possible backtrack.

Shortly after this transcript was unsealed, a letter from Mangione’s defense was made public on 18 June, stating “the defense respectfully withdraws CPL 250.10 notice at this time”. At approximately the same time, an order from Carro was posted stating: “In light of the defendant’s withdrawal of CPL 250.10 notice, the court’s previous order sealing certain transcripts, emails, and documents, remains in effect.”

Many believed that the defense’s letter meant they would not pursue any sort of psychiatric defense, with headlines effectively proclaiming that Mangione’s team had outright abandoned an extreme emotional disturbance strategy.

Gary Galperin, adjunct professor at Cardozo School of Law and former prosecutor, said he believes Mangione’s team will not now pursue a psychiatric defense.

As for the defense’s use of “at this time”, Galperin said, observers shouldn’t “read too much” into this phrasing and see it as a ploy that Mangione’s team might still try to use it later.

“It would really be gamesmanship on the defense part to try to leave open the option that they would try to reactivate their notice. I don’t believe that’s the case at all,” Galperin said.

But Mangione’s mental health could still be a huge part of the trial. One prominent murder case reveals how defense attorneys could still make an emotional distress defense but without a CPL.250 notice.

Gigi Jordan, who admitted to killing her autistic son at a tony Manhattan hotel in 2010, was found guilty of first-degree manslaughter rather than murder after jurors accepted her legal team’s extreme emotional distress defense – without a 250.10 notice, her lawyer said.

Ron Kuby, the veteran defense attorney representing Jordan, explained that withdrawing a CPL.250 notice is not the same thing as abandoning a psychiatric defense. The filing of a 250.10 notice, Kuby said, gives defendants “certain rights and imposes certain obligations”.

“What that means is you can have experts testify about your mental condition, you can introduce records of prior mental health treatment or issues, basically all of the other types of evidence we would consider to be psychiatric,” he said.

The prosecution, in turn, has the right to have their mental health expert interview a defendant. The defense also must provide prosecutors their psychiatric evidence, such as evaluations, records and other things they might rely on, in advance.

But, “the defense of EED is not dependent on section 250.10 notice”, Kuby said. “If you don’t file section 250.10 notice, if the defendant refuses to agree to a psychiatric interview by the prosecution, if you don’t want to hand over your defendant’s psychiatric materials, psychiatric records, or other mental health history, you can still put on an EED defense based on the prosecution’s evidence.”

The defendant’s own testimony could also show EED.

“Mangione himself can testify, and while he cannot testify about his mental health, he can demonstrate his mental health, or lack thereof,” Kuby said.

With Jordan, the jury simply came to its own conclusion about her mental health based on the evidence it heard in court.

“She refused to be interviewed by a defense mental health expert. She refused to be interviewed by a prosecution mental health expert. She insisted there was nothing wrong with her, that she acted in a completely rational manner under the circumstances, and she explained it to the jury at great length,” he said.

“She testified for days, and in the end, based both on the prosecution’s evidence and her own apparent state of unwell, the jury acquitted her of murder and found her guilty of manslaughter.”

If evidence presented at trial supports extreme emotional disturbance even without a 250.10 notice, Carro would have to give jurors an instruction about EED. Under this instruction, if jurors found Mangione committed murder, then they would have to consider EED. If jurors agreed there was EED, they would then convict on manslaughter.

The sealed proceeding also revealed deep concerns about Mangione supporters, whose attendance numbers at court proceedings regularly exceeds the double digits. Over the course of case proceedings, Mangione backers have been seen wearing pins and garments with messages of support for him.

Joel Seidemann, a prosecutor with the Manhattan district attorney’s office, said he’s also concerned about the possibility of “people who may be making threats” being present and that prosecutors might ask Carro to impanel an anonymous jury.

“Obviously there have been issues with respect to the presence of certain individuals in the courtroom,” Seidemann said. “I take it that the court will prohibit people from wearing T-shirts, carrying signs or alike at the trial itself.”

Even long before any trial begins, the Mangione saga is showing every sign of being one of the most eagerly watched in recent US criminal history.