GEOFF BENNETT: In our other top story tonight, the suspect in the killing of UnitedHealthcare CEO has been charged with murder in New York.

That's after he was found and arrested Monday in Pennsylvania.

AMNA NAWAZ: At his first court hearing this afternoon, the alleged gunman would not go quietly.

Twenty-six-year-old Luigi Nicholas Mangione arrived for his initial court appearance in Pennsylvania today.

LUIGI MANGIONE, Defendant: Completely unjust and an insult to the intelligence of the American people.

AMNA NAWAZ: The accused killer shouting and struggling with officers outside.

Inside, he remained defiant, contesting extradition to New York, where he faces his most serious charges.

Overnight, the first glimpses of a more cooperative Mangione, as he was seen hauled away in handcuffs and put behind bars after a six-day manhunt that led police more than 200 miles outside New York City.

OFFICER TYLER FRYE, Altoona, Pennsylvania, Police Department: We didn't even think twice about it.

We knew that was our guy, but he was very cooperative with us.

AMNA NAWAZ: Pennsylvania authorities have charged him with possession of an unlicensed firearm, forgery and providing false identification.

By late Monday evening, prosecutors in Manhattan added a charge of second-degree murder for the brazen, targeted killing of UnitedHealthcare CEO Brian Thompson on a New York street last week.

Mangione was born and raised in a wealthy Maryland family, attending an elite all-boys prep school in Baltimore, graduating as valedictorian in 2016.

He went to college at the University of Pennsylvania in the Ivy League, earning a bachelor and master's in computer science.

He also had a last-known address in Honolulu.

During that time in Hawaii, someone who knew Mangione said he suffered from severe back pain due to a childhood injury.

At one point, he left the island to get surgery on the mainland.

A photo atop an X account believed to be associated with Mangione shows an X-ray image of screws in a spine.

It's still unclear whether those problems were connected with his alleged targeting of Brian Thompson or UnitedHealthcare.

A law enforcement official told the Associated Press that part of a three-page handwritten document found on Mangione yesterday read -- quote -- "Frankly, these parasites simply had it coming."

And an internal police analysis viewed by The New York Times found that Mangione believed himself to be a -- quote -- "hero of sorts."

The shooting has ignited anger and resentment and even glorified violence toward the health care industry both online and elsewhere.

In New York this weekend, people even gathered to take part in a look-alike contest for the accused shooter.

All this has drawn condemnation, including from Pennsylvania Governor Josh Shapiro.

GOV.

JOSH SHAPIRO (D-PA): In America, we do not kill people in cold blood to resolve policy differences or express a viewpoint.

I understand people have real frustration with our health care system.

In some dark corners, this killer is being held as a hero.

Hear me on this.

He is no hero.

AMNA NAWAZ: Mangione is currently being held at a state correctional facility in Huntington, Pennsylvania, while the battle over his extradition plays out.