The chance sighting at the restaurant in Altoona led to a dramatic break in a challenging but fast-moving investigation that captivated the public in the five days since the shooting that shook the business world.

Luigi Nicholas Mangione, a 26-year-old Ivy League graduate from a prominent Maryland real estate family, had a gun believed to be the one used in last Wednesday’s shooting of Brian Thompson, as well as writings suggesting anger with corporate America, police said.

Late Monday, Manhattan prosecutors filed murder and other charges against Mangione, according to an online court docket. He remained jailed in Pennsylvania, where he was charged with possession of an unlicensed firearm, forgery and providing false identification to police.

Mangione was sitting in the rear of the McDonald’s wearing a blue medical mask and looking at a laptop computer, court documents said. A customer saw him and an employee called 911, said Kaz Daughtry, an NYPD deputy commissioner.

Altoona Police Officer Tyler Frye said he and his partner recognized the suspect immediately when he pulled down his mask. “We just didn’t think twice about it. We knew that was our guy,” he said.

When one of the officers asked if he’d been to New York recently, he “became quiet and started to shake,” according to a criminal complaint based on their accounts of the arrest.

In his backpack, police found a black, 3D-printed pistol and a 3D-printed black silencer, the complaint said. The pistol had a metal slide and plastic handle with a metal threaded barrel. He was taken into custody at about 9:15 a.m., police said.

Mangione had clothing and a mask similar to those worn by the shooter and a fraudulent New Jersey ID matching one the suspect used to check into a New York City hostel before the shooting, NYPD Commissioner Jessica Tisch said.

NYPD Chief of Detectives Joseph Kenny said Mangione was born and raised in Maryland, has ties to San Francisco and a last known address in Honolulu.

“Our family is shocked and devastated by Luigi’s arrest,” Mangione’s family said in a statement posted on social media late Monday by his cousin, Maryland lawmaker Nino Mangione. “We offer our prayers to the family of Brian Thompson and we ask people to pray for all involved.”

Mangione was arraigned and ordered held without bail during a brief court hearing. Asked if he needed a public defender, he asked if he could “answer that at a future date.” He eventually will be extradited to New York to face charges in connection with Thompson’s death, Kenny said.

Police found a three-page document with writings suggesting that Mangione had “ill will toward corporate America,” Kenny said.

The handwritten document “speaks to both his motivation and mindset,” Tisch said.

Altoona Deputy Chief of Police Derek Swope would not characterize the writings except to say they were voluminous.

“They were very detailed, and everything we have is going to be turned over to NYPD,” he told The Associated Press.

Mangione had a ghost gun, a type of weapon that can be assembled at home from parts without a serial number, making them difficult to trace, investigators said.

He also had a passport and $10,000 in cash — $2,000 of it in foreign currency, the local prosecutor said. Mangione, who said Hawaii was his most recent address, disputed the amount.

Thompson, 50, was killed last Wednesday as he walked alone to a hotel, where UnitedHealthcare’s parent company, UnitedHealth Group, was holding its annual investor conference, police said.

UnitedHealth Group thanked law enforcement in a statement. “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,” a company spokesperson said.

The shooting shook U.S. businesses and the health insurance industry in particular, causing companies to rethink security plans and delete photos of executives from their websites.

The shooter appeared to be “lying in wait for several minutes” before approaching the executive from behind and opening fire, police said.

Mangione attended an elite Baltimore prep school, graduating as valedictorian in 2016, according to the school’s website. He went on to earn undergraduate and graduate degrees in computer science in 2020 from the University of Pennsylvania, a school spokesperson said.

One of his cousins is a Maryland state legislator and his family bought a country club north of Baltimore in the 1980s. On Monday, police blocked off an entrance to the property, which public records link to the suspect’s parents. A swarm of reporters and photographers gathered outside.

Mangione went from Philadelphia to Pittsburgh after the shooting, and likely “was in a variety of locations across the state,” said Lt. Col. George Bivens of the Pennsylvania State Police said.

“Based on everything we have seen, he was very careful with trying to stay low profile, avoid cameras — not all that successfully in some cases, but that was certainly the effort he was making,” Bivens said.

In the days since the shooting, police turned to the public for help by releasing a collection of nine photos and video — including footage of the attack, as well as images of the suspect at a Starbucks beforehand.

Photos taken in the lobby of a hostel on Manhattan’s Upper West Side showed the suspect grinning after removing his mask, police said.

On Monday, police credited news outlets for disseminating the images and the tipster for recognizing the suspect and calling authorities.

Investigators earlier suggested the gunman may have been a disgruntled employee or client of the insurer. Ammunition found near Thompson’s body bore the words “delay,” “deny” and “depose,” mimicking a phrase used by insurance industry critics.

The gunman concealed his identity with a mask during the shooting yet left a trail of evidence, including a backpack he ditched in Central Park, a cellphone found in a pedestrian plaza and a water bottle and protein bar wrapper that police say he bought at Starbucks minutes before the attack.

On Friday, police said the killer had left the city soon after the shooting. Retracing the gunman’s steps using surveillance video, investigators say the shooter rode into Central Park on a bicycle and emerged from the park without his backpack. He made his way to a bus station that offers commuter service to New Jersey and routes to the East Coast, police said.