• Police in Altoona, Pennsylvania, are questioning a man in connection with the fatal shooting of UnitedHealthcare CEO Brian Thompson.
• Luigi Mangione was found with a gun similar to the one used to kill Thompson on Wednesday in New York City, as well as a silencer, a mask, a fake New Jersey ID and an apparent manifesto.
• Thompson's company, a subsidiary of UnitedHealth Group, is the largest health insurance company in the U.S.

A 26-year-old man identified as a "strong person of interest" in the killing of UnitedHealthcare CEO Brian Thompson in New York was denied bail as he was arraigned Monday evening in a Pennsylvania court on gun and forgery charges.

Hours later, the Manhattan District Attorney's Office filed murder and other charges against the man, University of Pennsylvania graduate Luigi Mangione, for the fatal shooting of Thompson last week.

Mangione was detained by Altoona, Pennsylvania, police on Monday morning after officers confronted him at a McDonald's and found a pistol, a silencer and seven 9mm full metal jacket rounds, multiple fake IDs and a U.S. passport in his backpack, authorities said.

The gun and the silencer had been 3-D printed, according to a criminal complaint against Mangione, a member of a prominent Baltimore family whose businesses have included country clubs, a nursing home, and a radio station.

"We didn't even twice about it," Altoona Patrolman Tyler Frye said about he and his partner recognizing Mangione at McDonald's from photos distributed by police in New York showing a person of interest in Thompson's slaying. "We knew that was our guy."

And the gun is "consistent" with the pistol armed with a silencer that was used by a masked gunman to fatally shoot Thompson on Wednesday morning outside the Hilton Hotel in midtown Manhattan, where the 50-year-old father of two headed to attend an investor meeting by his company's parent, UnitedHealth Group, New York police said.

Thompson's company, the largest private payer of health insurance benefits in the United States, had revenues of $281 billion and earnings of $16.4 billion in 2023.

"At this time, [Mangione] is believed to be our person of interest in the brazen targeted murder of Brian Thompson, CEO of United Healthcare," New York Police Department Commissioner Jessica Tisch told reporters at a news conference in Manhattan on Wednesday afternoon.

Mangione, who reportedly suffered from chronic back pain, was carrying a handwritten document that suggests "he has some ill will toward corporate America," a top NYPD official said.

Law enforcement officials said the manifesto referenced the health-care industry and also references avoiding detection, NBC News reported.

Before Mangione's arrest in Altoona, the NYPD did not know the identity of the person of interest the that department was seeking in connection with Thompson's slaying, officials said.

Officials said it would be up to Manhattan District Attorney Alvin Bragg to determine whether to charge Mangione in connection with Thompson's killing and what charges to file.

Blair County District Attorney Peter Weeks, whose office is prosecuting Mangione on the gun and forgery charges, said he expects Mangione to be charged with homicide "in the very near future."

Mangione's family in a statement said, "Unfortunately, we cannot comment on news reports regarding Luigi Mangione."

"We only know what we have read in the media. Our family is shocked and devastated by Luigi's arrest. We offer out prayers to the family of Brian Thompson and we ask people to pray for all involved," the statement said. "We are devastated by this news."

The statement was released by Mangione's cousin, Nino Mangione, who is a Republican member of the Maryland House of Delegates.

Pennsylvania Gov. Josh Shapiro said that Mangione in recent days had traveled between Philadelphia, where he went to college, and Pittsburgh, "making stops in between ... here in Altoona."

Mangione, a native of Towson, Maryland, who recently had lived in Honolulu, was approached by police after an employee of a McDonald's restaurant in Altoona reported a customer there was acting suspiciously at 9:14 a.m. ET.

About 1,000 miles away, Thompson's family was preparing to hold his private funeral in Minnesota on the same day.

Police arrived at the McDonald's to find Mangione, who was wearing a face mask, sitting at a table in the rear of the restaurant with a silver laptop computer, and a backpack on the floor near the table.

An officer "asked the male to pull down his medical mask so that he could see his face," according to a. criminal complaint.

"The male compiled and pulled down his mask; Affiant and Co-Affiant immediately recognized him as the suspect from [the] New York City incident after seeing photos of him released from media sources," the complaint said.

Officers then asked him for identification, and Mangione handed them a New Jersey driver's license bearing the name of a 26-year-old named Mark Rosario, the complaint said.

That is the same name from a fake New Jersey ID used by a man to check into a Manhattan hostel more than a week before Thompson's killing.

One of the Altoona police officers then asked Mangione "if he had been to New York recently and the male became quiet and started to shake," the complaint said.

After other police arrived at the McDonald's, and after his ID could not be matched with a known license, Mangione gave his real name.

An office asked Mangione "why he lied [about] his name and the Defendant replied 'I clearly shouldn't have,' " according to the complaint.

Mangione was then arrested on charges of forgery and false identification to law enforcement.

Police found the gun, silencer and bullets in his backpack, the complaint said.

He later was charged with firearms not to be carried without a license, and tampering with records or identification, in addition to the original charges.

NYPD investigators arrived hours later in Altoona, which is located in central Pennsylvania, about 100 miles east of Pittsburgh.

Mangione did not enter a plea when he was arraigned Monday evening in the Blair County Court House in Hollidaysburg.

Investigators are looking into a photo that Mangione posted in the profile of his X social media account, which shows an x-ray of a back with screws in it, whether it belongs to him or a relative, and if it is relevant to the shooting of Thompson, two senior law enforcement officials told NBC News.

Mangione received a Bachelor of Science in engineering, computer and information science, as well as a Master of Science for that concentration from the University of Pennsylvania in 2020.

Before his time at Penn, he graduated from the all-boys Gilman School in Baltimore, where he was a valedictorian, according to his LinkedIn profile.

A Stanford University spokesperson said a person with Mangione's name was employed in 2019 as a head counselor by that university's Pre-Collegiate Studies program. Mangione is known to have ties to San Francisco, which is located about 35 miles north of Stanford's campus.

In a statement Monday, UnitedHealth Group said, "Our hope is that today's apprehension brings some relief to Brian's family, friends, colleagues and the many others affected by this unspeakable tragedy."

"We thank law enforcement, and we will continue to work with them on this investigation," the company said. "We ask that everyone respect the family's privacy as they mourn."

Investigators are looking into how Mangione traveled to Altoona.

Police previously said the person who shot Thompson fled the area on a bike and pedaled into nearby Central Park.

The NYPD has said the suspect was spotted exiting the park on foot about 20 blocks north of the shooting scene, and that he then took a taxi north to the neighborhood of Washington Heights, where he was last seen entering the Port Authority Bus Terminal there.

Police have also said that the person of interest is believed to have arrived in New York City on Nov. 24 on a bus from Atlanta, and that he immediately went to the Hilton that same night and spent about a half hour walking around the streets nearby.

— Tom Winter of NBC News and Jonathan Dienst of WNBC contributed to this report.