A man arrested Monday on a gun charge in Pennsylvania has been identified as the suspect in the “brazen, targeted” fatal shooting last week of UnitedHealthcare CEO Brian Thompson in Midtown Manhattan, according to New York police officials.

Luigi Mangione, 26, was found at a McDonald’s in Altoona with a gun and a suppressor “both consistent with the weapon used in the murder,” New York Police Commissioner Jessica Tisch said at a news conference Monday, referring to a device that muffles the sound of a firearm.

Authorities also recovered a “fraudulent New Jersey ID matching the ID our suspect used to check into his New York City hostel before the shooting,” Tisch said, and “a handwritten document that speaks to both his motivation and mindset.” NYPD Chief of Detectives Joseph Kenny said those documents indicated “ill will towards corporate America.”

“These parasites had it coming,” one line from the document reads, according to a police official who has seen it. Another reads, “I do apologize for any strife and trauma, but it had to be done.” The document indicates the suspect acted alone, and that he was self-funded.

NYPD detectives are now en route to Pennsylvania, where they plan to interview the suspect, Tisch said.

The arrest seemingly brings to an end a sprawling manhunt that expanded beyond the nation’s largest city and across state lines. Scrutiny intensified as investigators recovered and analyzed various pieces of evidence, including shell casings from the scene of the shooting that police said had the words “delay,” “deny” and “defend” written on them.

The suspect was believed to have left New York City on an interstate bus, police officials previously said, after video cameras captured him entering the George Washington Bridge Bus Station on 178th Street but not leaving.

Mangione was arrested by the Altoona Police Department on firearms charges, the commissioner said. The weapon is a ghost gun – an untraceable, homemade weapon – capable of firing a 9 mm round, Kenny said.

The 26-year-old was picked up at in Altoona – about 230 miles from the hotel where the shooting occurred on December 4 – after a McDonald’s employee thought he resembled the man in New York Police Department photos and called police, officials said. Mangione was “sitting there eating” at the time, Kenny said, as officials praised the tipster for speaking up.

UnitedHealth Group hopes “today’s apprehension brings some relief to Brian’s family, friends, colleagues, and the many others affected by this unspeakable tragedy,” a spokesperson said in a statement.

“We thank law enforcement and will continue to work with them on this investigation. We ask that everyone respect the family’s privacy as they mourn,” the spokesperson said.

Here are other key developments:

• Police divers did not find the weapon used in the shooting in their search Sunday of a lake in Central Park, a law enforcement official told CNN. A day earlier, authorities searched the water near the park’s iconic boathouse and Bethesda Fountain. Also still missing is an electric bike the suspect rode toward Central Park, according to surveillance images released by authorities.
• A partial fingerprint and DNA recovered early in the search for the suspect have so far not yielded matches when compared against law enforcement databases, according to a law enforcement official. The fingerprint was recovered from a purported “burner phone” thought to belong to the suspect, and the DNA from a water bottle and energy bar wrapper the suspect is said to have bought.
• A backpack believed to be the suspect’s was recovered Friday in Central Park, a law enforcement source said. It contained money from the Monopoly board game, a law enforcement source told CNN, and a Tommy Hilfiger jacket, law enforcement officials briefed on the matter said.

‘You’re bound to make mistakes’

Authorities had known what the suspect looks like but not who or where he is. Over the weekend, they released new photos of him: in the backseat of a taxi and wearing a jacket while walking on the street. In both, he wears a hood and a face mask.

The public, too, had seen the suspect in surveillance photos and videos, including one with him pointing the weapon at Thompson’s back.

A determination of the suspect’s identity was expected to come soon, former FBI profiler Mary Ellen O’Toole said before Monday’s developments in Altoona.

“I’m thinking we’re going to know who this is within a matter of a few more days, if that,” she told CNN. “He’s completely outnumbered. With that kind of manpower behind their efforts, they’re going to come up with the information that identifies him.”

Authorities would have hung on the fugitives missteps, experts say.

“The ability to stand up against that kind of an investigation, one person can’t do it, no matter how arrogant you are,” O’Toole said. “You’re bound to make mistakes.”

Some of the suspect’s actions – such as pulling his mask down on camera and leaving behind inscribed shell casings that may point to a motive, a burner phone and a partial fingerprint on a water bottle – only added to the clues left behind for authorities.

Police also traced his movements before the shooting via a Greyhound bus originating in Atlanta and bound for New York City.

“The thing that works against the shooter is that law enforcement will get better, but the shooter can’t go back and undo what he’s already done,” O’Toole said.

The shooter appears to have perhaps only practiced such a killing before, rather than being an experienced assassin, O’Toole said. Leaving shell casings or Monopoly money behind for authorities would not typically align with the actions of a killer who wanted “to blend back into oblivion,” she said.

Police continue to look into whether words found on the casings – “Delay, deny, defend,” Kenny said – may point to a motive. A 2010 book critiquing the insurance industry is titled, “Delay Deny Defend,” a common description of its tactics.

Under pressure and running out of options

After several days of evading capture by the FBI, New York Police Department and other agencies, the psychological pressure of being on the run and the focus of a widespread search could have lead to errors, O’Toole said.

“It would be absolutely overwhelming and there’s nothing that he can do about it, and this is where he will make mistakes,” she said. “In the shoes of the shooter right now, he is dealing with emotions and consequences that I don’t think he anticipated at all.”

It’s possible the suspect could lose the critical thinking skills needed to strategically evade capture under the mounting pressure, the expert said.

“His options are getting fewer and fewer and fewer, and then on top of that, his ability to make good decisions is deteriorating,” O’Toole said.

“(With) the reality that he can never go back to a normal life the way it was before last week, all of those can result in very poor decision-making,” she added.

This story has been updated with additional information.