What's next for Luigi Mangione: A grand jury, extradition, and a possible psych defense

• Luigi Mangione remains held in Pennsylvania and charged with the murder of Brian Thompson.
• Former Manhattan prosecutors predict the extradition process could take months.
• Once in New York, he'll stay in the city's most notorious jail and could pursue a psych defense.

Since his arrest on Monday in the Manhattan killing of UnitedHealthcare CEO Brian Thompson, Luigi Mangione has been held in Pennsylvania's oldest jail.

The State Correctional Institution at Huntington, a sprawling red brick structure on the edge of the Allegheny Mountains, opened in 1889 as a reformatory for delinquent boys, and still features its original Queen Anne-style architecture.

Mangione will remain at that maximum-security jail as he fights extradition — a process that Manhattan defense lawyers and former prosecutors predict will take months.

"Whatever it is, it's going to be better than Rikers, and he'll be in no hurry to leave," veteran New York defense lawyer Ron Kuby told Business Insider, referencing Mangione's likely next placement, the city's notorious Rikers Island. Two weeks ago, a federal judge complained that court-ordered safety and use-of-force reforms at Rikers have proceeded at a "glacial pace."

Here's what longtime Manhattan attorneys predict will happen behind the scenes as Mangione, a 26-year-old Ivy League graduate from a wealthy Maryland real estate family, waits for his case to proceed from indictment to extradition and beyond.

First, a grand jury

Mangione is being held without bail on two felony complaints.

The first was drafted by police and prosecutors in Pennsylvania's Blair County. It alleges that on Monday, after being recognized by an employee at an Altoona McDonalds, he gave cops a fake ID and possessed in his backpack an unlicensed firearm — a part-metal, part 3-D-printed weapon described as a possible "ghost" gun.

The second complaint, drafted soon afterward by the NYPD and Manhattan prosecutors, also charges him with possession of a false ID and weapons possession but adds the top charge of second-degree murder.

Longtime Manhattan attorneys say a secret grand jury is likely already hearing evidence in Lower Manhattan on those charges.

Manhattan prosecutors will likely conclude their grand jury presentation against Mangione by the end of the week or by early next week at the latest, they said, estimating based on their own previous murder cases.

"They won't have full DNA and ballistic results yet," said one longtime defense attorney. The attorney asked to speak anonymously because they said they are under consideration to represent Mangione at his New York arraignment and in future proceedings.

At this early stage, prosecutors may not know for sure if the bullets fired at Thompson match the gun possessed by Mangione when he was arrested, the attorney said.

"But so far, they appear to have a ton of at least circumstantial evidence," they said. "But prosecutors only need to present a minimal amount of evidence" at this stage, to show that there is reasonable cause to believe Mangione committed the murder, they added.

Any indictment would remain sealed until Mangione faces a judge at his Manhattan arraignment.

A spokesperson for Manhattan District Attorney Alvin Bragg declined to confirm if a grand jury is hearing evidence or to comment on this story.

Next, an extradition battle

Meanwhile, Mangione is fighting extradition to New York, a process that will spool out over the course of many weeks, the legal experts predict.

On Tuesday, a Blair County judge got the ball rolling.

He gave local prosecutors 30 days to obtain what's called a governor's warrant, in which New York Gov. Kathy Hochul would request Mangione's return to New York.

"Once the indictment is voted, which could be very soon, they'll ship that paperwork up to the governor's office, where I"m sure it will be expeditiously processed and sent to Pennsylvania," said Daniel Bibb, a former Manhattan homicide prosecutor now in private practice.

"There has to be an indictment for there to be an extradition," Bibb said.

Hours after Mangione's arrest, Pennsylvania Gov. Josh Shapiro said Monday that the Commonwealth will cooperate in Mangione's extradition, and Blair County District Attorney Peter Weeks told reporters that he recognized New York's murder case takes precedence over his own forgery and gun-possession case.

Mangione's Pennsylvania attorney, Thomas Dickey, told Good Morning America on Wednesday that he will demand an extradition hearing so that Manhattan prosecutors will be required to begin divulging their evidence.

Dickey has repeatedly maintained his client's innocence in statements to reporters this week. He did not immediately respond to requests for comment on this story.

A formal extradition hearing, which has not yet been scheduled, will not focus on whether Mangione committed the murder, Bibb said.

"The issue in Pennsylvania will be whether the person named in the New York indictment is him. And that's pretty much the only inquiry," he said.

"I pretty much guarantee that you'll be seeing Mr. Mangione in New York within the next couple of months," Bibb predicted, depending on how much delay the Blair County judge is willing to tolerate.

An extradition battle could take months

Kuby, who has practiced criminal law in New York for more than 40 years, said that a creative defense lawyer could use appeals to drag an extradition battle on for many months.

"You hold the extradition hearing. You lose? You appeal to Pennsylvania's intermediate appellate court," he said. "You lose that, and you apply to the Supreme Court of Pennsylvania to hear the case."

In the early 1990s, Kuby and his partner, William Kunstler, were able to delay the New York-to-Florida extradition of Frank Strahan — a Harlem man arrested in the cold-case, 1946 shooting death of Miami's first black police officer — for nearly two years.

A defense lawyer can try to appeal an extradition all the way up to the US Supreme Court, Kuby said.

A potential psych defense

Once brought back to New York, Mangione would be quickly arraigned. The ensuing prosecution, however, could extend years if he decides to use a psychiatric defense and fights the charges at trial, experts said.

Given what investigators have described as the evidence implicating him in the shooting — including extensive surveillance video footage and what the NYPD Commissioner Jessica Tisch described as "anti-corporatist sentiment" in a hand-written document recovered at his arrest — Mangione's best chances at trial may be what's called an extreme emotional disturbance defense, they said.

Thompson, a 50-year-old father of two sons from Minnesota, was fatally shot on the sidewalk outside a UnitedHealthcare shareholders meeting, where he'd been set to speak.

In his online posts, Mangione, the scion of a wealthy and prominent Baltimore family, had complained about his chronic back pain and the healthcare system.

A so-called EED defense would ask jurors to find Mangione guilty of a lesser charge of manslaughter, arguing he was so emotionally disturbed at the time that he believed he had to kill Thompson.

"It might be a long shot," said the attorney who requested anonymity due to their potential connection to the case.

"But by all accounts, he went off the grid six months ago, and that was uncharacteristic of him, as was any act of violence," they said.

"He may well have had a psychotic break."