Luigi Mangione has suffered a major court setback after a judge ruled that damning evidence recovered during his arrest can be presented to the jury.
Judge Gregory Carro decided jurors will be shown the notebook that was found in Mangione's backpack by police in which the Ivy League graduate allegedly wrote he wanted to 'whack' a senior figure in the health insurance industry.
The 9mm 'ghost gun' found inside Mangione's backpack - the alleged murder weapon - will be allowed into evidence, the judge ruled.
However other items such as a magazine of bullets wrapped in underwear, a cellphone, passport and wallet will not go before the jury.
The decision is a huge blow to Mangione in his state case in New York for allegedly shooting UnitedHealthcare executive Brian Thompson outside a hotel in Manhattan in December 2024.
Mangione, who turned 28 earlier this month, has pleaded not guilty to murder in the second degree and to weapons charges along with possession of a forged instrument.
He is due to go on trial in September.
Late last year, Judge Carro held a nine-day hearing to determine what evidence could be allowed after Mangione's lawyers claimed his constitutional rights against illegal search and seizure were violated.
Luigi Mangione appeared in court on Monday as a judge ruled on whether key evidence from his arrest can be shown to jurors
Mangione, pictured in a court sketch in April, is accused of fatally shooting UnitedHealthcare executive Brian Thompson in December 2024
They claimed that police in Altoona, Pennsylvania, did not have a warrant to search Mangione when he was arrested in a McDonald's in the town five days after the shooting.
Among the contents of the bag was a red notebook which prosecutors called a 'manifesto' - Mangione's lawyers called it a 'journal'.
Writing in October 2024, Mangione said he wanted to 'whack' the chief executive of an insurance company at its annual 'bean counter conference'.
Six weeks later Thompson, 59, a father-of-two, was shot outside the Hilton Midtown during a UnitedHealthcare conference.
Another October entry allegedly read that the investor conference was 'a true windfall.'
The journal stated: 'It embodies everything wrong with our health system'.
In another entry from August 2024, Mangione allegedly wrote: 'I finally feel confident about what I will do. The details are coming together.
'And I don't feel any doubt about whether it's right/justified. I'm glad-in a way-that I've procrastinated bc it allowed me to learn more about (UnitedHealthcare).
Judge Gregory Caro will rule on whether prosecutors can show the jury the contents of Mangione's backpack when he was arrested in December 2024. A backpack recovered by police in Central Park during the investigation
The 28-year-old Ivy League graduate was charged with murder in the second degree and weapons charges along with possession of a forged instrument, all of which he denies, over the death of United Healthcare CEO Brian Thompson
'The target is insurance. It checks every box.'
The other items in the backpack included a 9mm 'ghost gun', or a 3D printed firearm with no serial number, a loaded gun magazine wrapped in a pair of underwear and silencer.
Police who arrested Mangione said that the bullets in the magazine convinced them he was the killer.
According to prosecutors, the bullets used to kill Thompson had the words 'delay', 'deny' and 'depose' written on them in reference to the language used to deny health insurance claims.
Mangione recently caught a break in the separate federal case, which is taking place in New York in a courtroom a few blocks from the state court.
US District Judge Margaret M. Garnett dismissed four of the federal counts including murder through the use of a firearm and a related firearms offense.
Critically, the dismissal of the murder charge meant Mangione is no longer eligible for the death penalty.
Mangione still faces two counts of interstate stalking, which carry a maximum sentence of life in prison without parole.
UnitedHealthcare CEO Brian Thompson was gunned down on his way to a conference in Manhattan in 2024
The federal case is due to go on trial next year once the state matter is concluded.
Mangione is currently being held at the grim Metropolitan Detention Center, a federal prison in Brooklyn whose previous inmates included R. Kelly and Diddy.
Ahead of his hearing on Monday, Judge Garnett ordered the Bureau of Prisons to make sure Mangione could wear civilian clothes.
She said that he has to be given a suit, one shirt, a pair of socks and a pair of shoes, but no laces.