Luigi Nicholas Mangione, the man charged with the murder UnitedHealthcare CEO Brian Thompson, is a former high school valedictorian and Ivy League graduate, social media accounts and court documents reveal.
The 26-year-old was last known to be living in Honolulu, has no prior arrest history and grew up with a wealthy and influential family in Maryland.
Following a days-long search across state lines for Mr Thompson's alleged shooter, Mr Mangione was arrested while eating at a McDonald's restaurant in Altoona, Pennsylvania.
Luigi Mangione, originally from Maryland, was arrested in Pennsylvania. (Supplied: X)
Police arrested Mr Mangione after a McDonald's worker recognised him from CCTV images circulated to the media.
Mr Mangione is currently jailed in Pennsylvania on gun charges and New York prosecutors have now filed murder charges against him, according to an online court docket.
Former classmates and friends have expressed their surprise at the news of Mr Mangione's arrest as more details emerge about who he is.
Here's what we know about Luigi Mangione.
Who is Luigi Mangione?
Mr Mangione was born and raised in Maryland, has ties to San Francisco and a last known address in Honolulu, Hawaii, police said.
Luigi Mangione, pictured in a social media photo posted in 2019, was arrested after being spotted at a McDonald's, police say. (Facebook: Luigi Mangione)
According to what appears to be his LinkedIn account, his last known place of work was a company in California called TrueCar, a website for buying new and used cars, where he worked as a data engineer.
Mr Mangione attended an elite Baltimore prep school, graduating as valedictorian in 2016, according to the school's website.
In his graduation speech, he talked about his classmates' "incredible courage to explore the unknown and try new things".
Freddie Leatherbury, a former classmate, told AP he was a "smart, athletic, and friendly student who came from a wealthy family".
"Quite honestly, he had everything going for him," he said.
Mr Leatherbury said he was stunned when a friend shared the news of their former classmate's arrest.
"He does not seem like the kind of guy to do this, based on everything I'd known about him in high school," Mr Leatherbury said.
He went on to earn undergraduate and graduate degrees in computer science in 2020 from the University of Pennsylvania, a school spokesman said.
While attending the university, he worked as a teaching assistant and founded a video game development club.
Through his cousin Nino Mangione, who is a Maryland state legislator, his family released a statement following Mr Mangione's arrest.
"Our family is shocked and devastated by Luigi's arrest," he posted to social media.
"We offer our prayers to the family of Brian Thompson and we ask people to pray for all involved."
Mr Mangione's grandfather, Nick Mangione Senior, was a millionaire real estate developer and philanthropist, according to a 1995 profile by the Baltimore Sun.
AP reported that one of his cousins was 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.
Lugui Mangione posted this photo at Stanford University in 2019 on his Facebook account. (Supplied: Facebook)
What did police find on him?
The Altoona McDonald's restaurant where an employee alerted authorities to Mangione's presence. (AP: File)
Mr Magione was found with a 3D-printed gun and silencer, a large sum of cash, mask and writings linking him to the shooting, according to police.
The gun is believed to be the one used in the shooting last week.
Mr 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.
Police found a three-page document with writings suggesting that Mangione had "ill will toward corporate America," NYPD Chief of Detectives Joseph Kenny said.
Chief of Detectives Joseph Kenny said New York would seek to extradite Luigi Mangione from Pennsylvania. (AP: New York City Mayor's Office)
The handwritten document "speaks to both his motivation and mindset," NYPD Commissioner Jessica Tisch said.
Blair County District Attorney Peter Weeks said in court that Mr Mangione was carrying a passport and $10,000 in cash — $2,000 of it in foreign currency.
Mr Mangione disputed the amount.
He was also found with a box of masks, the prosecutor said.
Court documents say he was taken into custody on charges of forgery and false identification to law enforcement.
What is a ghost gun?
Mr 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.
"As of right now, the information we're getting from Altoona is that the gun appears to be a ghost gun that may have been made on a 3D printer, capable of firing a 9 mm round," Chief Kenny said.
What happens now?
According to AP, Mr Mangione was arraigned in Pennsylvania and held without bail in a Pennsylvania court.
Asked if he needed a public defender, he asked if he could "answer that at a future date".
On Tuesday morning, AP reported that video posted on the social platform X showed a handcuffed Mr Mangione arriving at the Blair County Courthouse in Hollidaysburg, Pennsylvania.
"At some point, we'll work out through extradition to bring him back to New York to face charges here, working with the Manhattan District Attorney's Office," Chief Kenny said.
Police are also investigating the path the suspect allegedly took from Manhattan to Pennsylvania.
"This just happened this morning. We'll be working, backtracking his steps from New York to Altoona, Pennsylvania," Chief Kenny said.
How did the investigation unfold?
This undated photo released by the New York Police Department shows Mangione in a taxi. (AP: NYPD)
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 recognising the suspect and calling authorities.
The NYPD released this image of a man wanted for questioning. (Supplied: NYPD)
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 phone 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 then walked a couple of blocks and got into a taxi before arriving at the George Washington Bridge Bus Station, which is near the northern tip of Manhattan and offers commuter service to New Jersey and bus routes to Philadelphia, Boston and Washington, Chief Kenny said.
The FBI announced late on Friday that it was offering a $50,000 reward, adding to a reward of up to $10,000 that the NYPD offered.
Court documents reveal Mr Mangione was sitting at a table in the rear of the McDonalds wearing a blue medical mask and looking at a silver laptop computer and had a backpack on the floor.
When he pulled down his mask, Altoona police officers "immediately recognised him as the suspect" in the killing of UnitedHealthcare CEO Brian Thompson, the documents say.
Asked for identification, Mr Mangione provided officers with a fake ID — a New Jersey driver's license bearing another name and the incorrect date of birth.
When an officer asked if he'd been to New York recently, he "became quiet and started to shake", according to a criminal complaint based on police accounts of the arrest.
UnitedHealth Group comments on the arrest
UnitedHealthcare's chief executive Brian Thompson was shot dead out the front of a Manhattan hotel. (Supplied: UnitedHealth Group via AP)
In a statement released after the arrest, a spokesperson for UnitedHealth Group, where Brian Thompson was CEO of the insurance division, 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 will continue to work with them on this investigation. We ask that everyone respect the family's privacy as they mourn."
Governor of Pennsylvania Josh Shapiro told AP the person who notified police about Mr Mangione was a "hero".
"A Pennsylvania resident saw something early this morning and said something to our local police," Mr Shapiro said.
"In some dark corners, this killer is being hailed as a hero. Hear me on this, he is no hero," the Democrat continued.
"The real hero in this story is the person who called 911 at McDonald's this morning."