The Ivy League murder suspect displayed arrogance and did not anticipate being caught, according to a body language expert.

A body language expert believes that Luigi Mangione's body language as he was escorted into a Pennsylvania courthouse reveals the accused killer's mindset.

In Altoona, Pennsylvania, on Monday, Mangione was arrested after a McDonald's customer recognized him as the suspect in the shooting of UnitedHealthcare CEO Brian Thompson in Manhattan.

In Pennsylvania, he was charged with forgery and carrying a firearm without a license. Despite this, he has not waived his right to an extradition hearing to face murder charges in New York.

On Tuesday, Mangione, a 26-year-old man, was escorted into Blair County Court and was wide-eyed with his head on a swivel as he shouted at surrounding reporters. Susan Constantine, who spoke to Planet Chronicle Digital, said that Mangione's "rigidity" suggested he was fearful.

Through a slight raise of his chin and looking down his nose at his surroundings, Mangione conveyed a sense of arrogance and pompousness.

"Remember that we're dealing with a person who believes they have been wronged in their own mind, and we don't yet know the specific reasons why. Additionally, this person has adopted a radical belief system and feels that they must act on their own behalf."

Mangione's chin is pointed up in his mugshot photos, whether he is wearing an orange jumpsuit or a blue suicide prevention smock, as Constantine noted.

""When we see the chin up, we can see the Adam's apple pop out, and his nose pops up in the air, which is a sign of pride and arrogance and pompousness," she said."

The suspect's expression in the photograph of him flirting with a hostel employee in New York before the Dec. 4 assassination is vastly different from his current demeanor.

"This was not the sinister killing face – it was him, his charming and flirty personality, the one that everyone is talking about," Constantine said. "He's a great guy. They like him. He's engaging and speaks confidently in front of the public."

Cubing is the term for disassociating, which these killers do. They have one personality when actively pursuing, but another when in relationships. They are able to separate from the sinister thoughts and radicalism that flood their minds.

"Suddenly, his smile turned into a frown during his perp walk, with droopy cheeks and a more rigid and tense facial expression that was different from what we had seen before. This was a game over expression."

The footage of the suspect's confident demeanor during the shooting reveals the meticulous planning that went into the attack.

"Constantine had meticulously prepared for the engagement, which was not a spontaneous occurrence. He had carefully planned and measured every aspect of his performance, resulting in a controlled body language and a calm demeanor. His energy level was low because he was in hyper-focus, ready to execute his plan flawlessly."

According to Constantine, Mangione's body language during his perp walk and in a police photograph taken the day before suggested that he did not anticipate being arrested by law enforcement.

"Constantine stated that people who are being deceptive exhibit certain behavioral signatures and cognitions. When they are caught, they display rigidity by sitting up straight and becoming very militant. This suggests that their structure is very robotic."