A body language expert said that Luigi Mangione displayed several “red flags” when he was arrested by police in Pennsylvania after allegedly killing UnitedHealthcare CEO Brian Thompson in December 2024.

Prosecutors released body camera video on Tuesday that shows police officers confronting Mangione at a McDonald’s in Altoona, Pennsylvania, on Dec. 9, 2024. An employee at the fast-food restaurant reportedly recognized Mangione and told a co-worker, who then alerted police.

Body language expert Susan Constantine told Fox News Digital that Mangione displayed “red flags” when police first confronted him at the McDonald’s and said someone reported him as being suspicious.

“So he does this expression on his face when he’s asked that question, is that frozen freeze response. Like that, right? Eyes wide open, mouth drops. And then he doesn’t deny. He doesn’t ask any questions. He doesn’t defend himself,” Constantine said. “He doesn’t say anything. And the fact that he doesn’t say anything, all of those were red flags because you would naturally be curious.”

NYC PROSECUTORS SHARE EVIDENCE PHOTOS REVEALING LUIGI MANGIONE’S POSSESSIONS AT TIME OF ARREST

Constantine also pointed out how Mangione “positioned himself in the corner conspicuously” and was fully masked. Constantine said that concealment is one of the ways she can determine “dangerous intent,” which she says Mangione is doing.

“So the fact that he was hiding in the back, that’s one pin, right? Then he’s got the concealment of the clothing. He’s got his little hat down over his eyebrows, then he’s got the mask on, and he’s looking down, right? So he’s trying to remove himself from ever being noticed, and that’s what he was doing,” Constantine said.

She added that Mangione knew it was “game over” when he went to grab the driver’s license to hand to police, and had a “fear response” when approached by the officer.

MANGIONE DEFENSE TEAM ACCUSES POLICE OF FABRICATING MOTHER’S QUOTE IMPLICATING HIM IN CEO MURDER CASE

“At that point, I knew he knew it was game over just because of his body language of being more in a low confidence. You know, his shoulders are kind of pulled in, he’s kind of huddled together. He’s not leaning out and just, you know, going on his computer just doing work. There were so many signals,” Constantine said. “All of those things led to this is an anomaly compared to everybody else that was in that restaurant. That’s what it is. It’s an anomaly.”

The McDonald’s employee who made the initial 911 call identified Mangione as the suspect in Thompson’s death, according to a transcript of the call.

WATCH: Police confront Luigi Mangione at Pennsylvania McDonald’s

“I’m a manager at Plank Road McDonald’s out here on the boulevard,” a McDonald’s manager told the 911 dispatcher. “And I have a customer here, that some other customers were suspicious of, that he looks like the CEO shooter from New York.”

Altoona Police Officer Christy Wasser testified in court on Monday that she found a magazine with bullets wrapped in wet underwear that was inside Mangione’s backpack.

CLICK HERE TO DOWNLOAD THE FOX NEWS APP

“There was another magazine hidden in his underwear,” Wasser can be heard saying.

Mangione faces numerous state and federal charges, including the possibility of the death penalty being handed down.