Luigi Mangione’s defense attorney in Pennsylvania continues to argue that Altoona police unlawfully detained the murder suspect and searched his belongings when they identified him at a McDonald’s following a tip.

Mangione, 26, is charged with first-degree murder in furtherance of an act of terrorism, stalking and a slew of other state and federal charges in both New York and Pennsylvania, for allegedly gunning down UnitedHealthcare CEO Brian Thompson, a married father of two, on a sidewalk in Manhattan in December 2024.

Now his attorney says authorities’ use of the word “manifesto” to describe Mangione’s writings allegedly found in his backpack during his arrest on Dec. 9 is “incorrect.”

“The use of this characterization of the defendant’s alleged personal experiences and writings is incorrect, improper and without justification and has no probative value,” Altoona-based defense attorney Thomas Dickey said in a Tuesday court filing. “Defendant believes that this characterization was done so solely for the purpose to prejudice the defendant and put him in a negative light before the public, all in an effort to prejudice any potential jury pool.”

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Mangione allegedly shot Thompson outside the Manhattan hotel where UnitedHealthcare’s annual shareholder conference was being held, in an act prosecutors believe was meant to send a message to the healthcare insurance industry based on a manifesto found on the suspect when he was arrested days after Thompson’s murder.

In his writings, Mangione apparently expressed his grievances with the healthcare industry — specifically naming UnitedHealthcare and the shareholder conference where Thompson was headed in New York at the time of the assassination.

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Dickey is asking the court not to describe Mangione’s alleged writings as a “manifesto.” He is also asking the court to suppress various other evidence, including what Dickey describes as a warrantless search of the suspect’s backpack, statements made to police during his arrest and DNA evidence. 

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Mangione’s attorney argued that Mangione had been improperly detained and arrested at the McDonald’s, so certain evidence collected during that arrest should not be submitted as evidence against his client.

The 26-year-old suspect has a degree from the Ivy League University of Pennsylvania and attended an elite private high school in Baltimore.

Despite some supporters’ characterization of him as an anti-capitalist crusader, he allegedly stopped at a New York City Starbucks for coffee minutes before the murder and was ultimately arrested while eating hashbrowns at McDonald’s.

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Mangione is accused of “meticulously” planning the murder with the motive of igniting a “public discussion about the healthcare industry,” according to the U.S. Department of Justice.

New York prosecutors said Mangione plotted to travel to New York; find Thompson, a Minnesota resident in town for UnitedHealthcare’s annual shareholder conference; and kill him. Mangione allegedly shot Thompson from behind with a 3D-printed ghost gun and suppressor. 

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The NYPD released a still image from surveillance video, showing him pulling his face mask down and smiling while flirting with a clerk at the check-in of the Manhattan hostel where police say he stayed for the murder. It went viral and immediately attracted a wave of support online for the accused killer.

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The suspect allegedly fled the scene of Thompson’s murder, rode a bike to a bus station and took a bus to Altoona, where he was ultimately identified and arrested.

Mangione is originally from Maryland and recently lived in California and Hawaii. He graduated as valedictorian from the Gilman School, a private, all-boys high school in Baltimore, in 2016.

Mangione went on to receive his bachelor’s and master’s degrees in computer science from the University of Pennsylvania in 2020.

Fox News Digital’s Michael Ruiz contributed to this report.