Luigi Mangione will use a psychiatric defense at his upcoming trial in the killing of UnitedHealthcare CEO Brian Thompson, a Manhattan judge revealed at a bombshell hearing Wednesday.

Manhattan Supreme Court Justice Gregory Carro said Mangione’s lawyers will argue that he was in the throes of an “extreme emotional disturbance” and experienced a “profound loss of self control” when he gunned down Thompson on a Midtown sidewalk in December 2024.

The eyebrow-raising legal gambit would knock the charge down to manslaughter instead of murder — carrying less prison time — if jurors buy it.

Carro said Mangione’s attorneys must reveal more details to Manhattan prosecutors by Thursday about the specifics of their mental health defense at the upcoming Sept. 8 trial.

“They need to know what malady this defendant suffers [from], and how that triggered extreme emotional disturbance at the time of the occurrence,” the judge said.

Prosecutors will likely counter Mangione’s defense strategy by stressing the many steps he allegedly took to plan the cold-blooded murder, including lying in wait for Thompson for an hour outside the Hilton hotel where UnitedHealthcare was holding its annual investor conference. 

Jurors will also see Mangione’s notebook in which the accused killer mused about killing a health insurance CEO to draw attention to what he dubbed a “parasitic” industry.

Cops found the red journal, zip ties and rolls of duct tape inside the privileged anti-capitalist’s backpack when they nabbed him while he was having breakfast at an Altoona, Pa. McDonald’s after a dramatic five-day manhunt.

Police also found a partially 3D-printed pistol — the alleged murder weapon — in Mangione’s belongings, authorities said.

Mangione, who had allegedly been staying in an Upper West Side hostel using a fake name, escaped from the scene of the caught-on-camera West 54th Street killing on an electric bike, riding through Central Park, where he left behind a bag full of monopoly money, court papers state. 

He then allegedly hopped into a taxi and was dropped off on West 178th Street in Washington Heights, before fleeing the state by train to Pennslyvania.

Experts polled by The Post Wednesday were split on whether the legal strategy would be successful.

“I think a jury is going to have a difficult time with this,” said Heather Cucolo, a criminal law professor at New York Law School.

“He had the materials, he had had had a plan, had to put everything together. All of that is going to cut against what I think jurors, laypersons are generally going to believe,” Cucolo said.

But defense attorney Ron Kuby called the psych argument “sort of the perfect defense” — and added that it would allow Mangione’s defense team to highlight the perils of the healthcare system as part of their case.

“You need to make the jury want to find in your client’s favor,” Kuby told the Post. “One way to do that is to present your client in a sympathetic light, and another way is portraying the dead person as someone who was complicit in his own destruction.”

Mangione has pleaded not guilty in parallel state and federal cases to charges of fatally shooting Thompson, a 50-year-old father-of-two, from close range on Dec. 4, 2024 in the shocking daytime assassination. 

A mountain of physical evidence ties Mangione to Thompson’s execution, including his DNA recovered from a cellphone, water bottle and piece of gum discarded by the masked gunman fleeing the scene, prosecutors have said.

Bullet casings recovered from the scene had the words “delay” and “deny” etched into them, echoing a phrase that insurance industry critics say companies use to describe trying to avoid paying out claims.

Mangione faces life in prison if convicted of murder in the state case, or a maximum of 25 years if the charges are reduced to manslaughter.