An email sent to past students by the headmaster of the Gilman School, the private all-boys school in Baltimore, Maryland, previously attended by Luigi Mangione calls the fatal shooting of United Healthcare CEO Brian Thompson and the subsequent arrest "deeply distressing".

"We recently became aware that the person arrested in connection with the killing of the UnitedHealthcare CEO is a Gilman alumnus," Henry Smyth, the head of the school, wrote.

"We do not have any information other than what is being reported in the news," he said.

"This is deeply distressing news on top of an already awful situation. Our hearts go out to everyone affected," he added.

"Here on campus, our focus will remain on caring for and educating the boys."

Jessica Parker
Reporting from Pennsylvania

As I write, we’re about 45 minutes drive away from Altoona, Pennsylvania. Following the news that a suspect in the shooting of Brian Thompson had been arrested in the city, we set off from our office in Washington DC.

The team – myself, a producer and a cameraman – will head to the places that are of interest to this investigation to try and discover more about today’s events. That will include the McDonald's where Luigi Mangione was arrested and the police station where he’s being questioned.

It’s not clear how long Mangione will be detained in Pennsylvania before potentially being taken to New York where the shooting happened last week. We know that officers from the NYPD have headed to Altoona – as will much of US media following the huge interest in this story.

The BBC has heard from the University of Pennsylvania, the Ivy League attended by Mangione, which confirmed details that had appeared on his social media accounts.

According to a spokesperson from the university, Mangione received his bachelor of science in engineering with a major in computer science and graduated in May 2020.

The BBC has also learned additional employment details about Mangione and confirmed that he was employed as a head counselor in the Stanford Pre-Collegiate Studies programme in 2019.

Prior to college, Mangione graduated valedictorian - typically a student with the highest grades - from Gilman School, an elite all-boys private high school in Baltimore, Maryland.

On Wednesday 4 December UnitedHealthcare CEO Brian Thompson was shot dead outside of a hotel in New York City. Today, police announced they had arrested 26-year-old Luigi Mangioni in connection with the shooting. Here's how the past week unfolded:

• 4 December: Thompson is shot at around 06:45 EST (11:45 GMT).
• 4 December: At 06:48, the suspect enters Central Park. Shortly before 07:00 he left the park and at 07:04 took a cab to the Port Authority bus terminal. He was not spotted on any cameras leaving the station, so the presumption is that he left on a by bus.
• 4 December: Thompson was pronounced dead at Mount Sinai West Hospital
• 5 December: Police released two new photos showing a "person of interest", wearing dark clothing but no face mask.
• 5 December: Three shell casings found at the scene of the crime had the words "deny", "defend" and "depose" written meticulously on them with a marker pen
• 6 December: NYPD says the suspect arrived in the city on a bus that originated from Atlanta 10 days before the shooting. It is unclear where the suspect caught the bus along its route
• 6 December: A backpack that police believe belonged to the suspect is found in Central Park and sent for forensic testing. Police say the suspect scoped the area before implementing the attack
• 8 December: Search for murder weapon under way in Central Park with a team of divers deployed
• 9 December: Mangioni is apprehended at a McDonald's in Altoona, Pennsylvania, after an employee there spotted him and alerted the police. They call him a "strong person of interest"

Details about Mangione have continued to emerge, including the name of the private high school he attended in Baltimore, Maryland - Gilman School - where he graduated at the top of his class in 2016.

After it was revealed that Mangione is an alumni there, the school sent out an email to past students on Monday.

"This is deeply distressing news on top of an already awful situation," Henry Smyth, the head of school, wrote. "Our hearts go out to everyone affected."

In a statement, the Altoona Police Department says its officers were dispatched to a McDonald's at 09:14 local time after receiving reports of a male that matched the description of the suspect in the killing of UnitedHealthcare CEO Brian Thompson.

They then made contact with the man and arrested him on "unrelated charges", police say.

"At this time, the Altoona Police Department is cooperating with local, state, and federal agencies," they say, adding that they will release more information later this evening.

Altoona is about 277 miles (445km) west of New York City, where the shooting took place.

Image source, CBS

Ghost guns are privately made firearms that are unregistered and largely untraceable.

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Tutorials online explain how to assemble the pieces into a fully functioning firearm with just basic tools in less than an hour.

Experts have called ghost guns the fastest-growing gun safety problem in America, with the number recovered from crime scenes having increased by more than 1,000% since 2017, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) said last year.

Ghost guns are not federally restricted, but at least 15 states have policies that do regulate them.

Read more on ghost guns and why the government has been trying to crack down on them

UnitedHealthcare has reacted to the arrest of a suspect in relation to Brian Thompson's killing.

In a statement sent to the BBC, a spokesperson for the company says they hope the arrest will bring "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," they add.

"We ask that everyone respect the family’s privacy as they mourn.”

Madeline Halpert
Reporting from New York

We've been combing through the social media accounts of Luigi Mangione who police said was a "strong person of interest" in the UnitedHealthcare CEO's shooting.

The 26-year-old is a graduate of the Ivy League University of Pennsylvania, where he studied computer science, according to social media profiles that match the police description of the suspect.

He grew up in Baltimore, Maryland, where he attended a private, all-boys high school, according to his LinkedIn account.

The same account says he worked as a data engineer for TrueCar, a digital retailing website for new and used cars.

Posts on Mangione's social media accounts suggest that he had fallen out of touch with family and friends. In a post tagging Mangione on X, someone wrote: "Hey, are you ok? Nobody has heard from you in months, and apparently your family is looking for you."

Mike Wendling
US digital reporter

Police say a document written by Luigi Mangione does not include specific threats to other people, "but it does seem he has some ill will towards corporate America".

Online, there are other possible insights as to Mangione’s thinking. A person matching his name and photo had an account on Goodreads, a user-generated book review site, where he gave four stars to Industrial Society and Its Future by Theodore Kaczynski – more popularly known as the Unabomber manifesto.

Starting in 1978, Kaczynski carried out a bombing campaign in the US that killed three people and injured dozens of others, until he was arrested in 1996.

In his review of the manifesto, Mangione wrote: “It's easy to quickly and thoughtlessly write this off as the manifesto of a lunatic, in order to avoid facing some of the uncomfortable problems it identifies. But it's simply impossible to ignore how prescient many of his predictions about modern society turned out.

“He was a violent individual - rightfully imprisoned - who maimed innocent people. While these actions tend to be characterized as those of a crazy luddite, however, they are more accurately seen as those of an extreme political revolutionary.”

In recent years Kaczynski’s story and his 35,000-word manifesto have been repurposed by people, particularly young men, who are deep into online subcultures. Sometimes he’s been reused as a meme, and in darker posts the bomber, who died in prison in 2023, has been lauded as a hero.

Police in New York have just wrapped up a news conference, where they revealed the identity of the suspect apprehended in the killing of UnitedHealthcare CEO Brian Thompson.

Here is what we learnt:

• The suspect of interest has been named as 26-year-old Luigi Mangione
• Police say that he attended college in Pennsylvania. He was born in Maryland, with a last known address in Honolulu, Hawaii. He also has ties to San Francisco, California
• The man was apprehended at a McDonald's in Altoona, Pennsylvania, after an employee there spotted him and alerted the police
• He was found with a firearm and a suppresser, as well as several IDs - one that had his real name, and another that was fake. They include a US passport and a fraudulent New Jersey ID that was used to check into the New York City hostel, where the suspect was spotted before the shooting
• The gun the suspect was found with was a ghost gun, likely "made on a 3D printer" capable of firing a 9mm round, police say
• Police also say he was found with handwritten documents - also described as a "three-page manifesto" - that spoke to his "motivation and mindset", and that he "seems to have ill will towards corporate America"
• Mangione does not have a criminal record. Police have arrested him on firearms charges
• Police revealed that finding the 26-year-old was a complete surprise, and that they did not have his name on a list of suspects prior to today

The press conference has just wrapped up, with senior members of the New York Police Department speaking alongside Mayor Eric Adams.

We'll continue to bring you updates on this breaking news, stick with us.

Police say they found a hand-written three-page manifesto on Mangione when arresting him.

"We believe, at this point, our investigation is leaning toward he was acting alone," police say.

"As far as the manifesto, like I said, I don't have complete details of that. It's in the possession of the Altoona Police."

Finding Mangione appears to be a complete surprise. Police say they did not have his name prior to today.

Chief of detectives Kenny says that there is no information they can provide at the moment on what happened during the arrest, which was carried out by Altoona Police.

He adds that the investigation is still ongoing, part of which includes officers combing through Mangione's social media.

"Preliminary, it seems like he had some ill will towards corporate America," Kenny says, but adds that further details will come out as part of the investigation.

Police say that Mangione was found at a McDonald's in Pennsylvania while sitting and reading.

Although he was hundreds of miles from the scene of the crime in New York, police say they do not believe he was trying to flee the country.

He is currently facing gun charges, police say.

They add that they found a ghost gun likely "made on a 3D printer", capable of firing a 9mm round and a suppressor.

Mangione does not have a criminal record.

Police are now taking questions from the media, with the first one about a document that allegedly explains the suspect's motivations.

"We don't think there's any specific threats to other people mentioned in that document," police say, "but it does seem he has some ill will towards corporate America".

Police commissioner Tisch says the arrest of Mangione was the "combination of old school detective work and new age technology".

"The images that we shared with the public were spread far and wide, and the tips we received led to the recovery of crucial evidence," she says.

"We should never underestimate the power of the public to be our eyes and our ears in these investigations."

Tisch says this is the third time in as many weeks that someone from the public gave police information that led to the arrest of a suspect.

We are now hearing from chief of detectives at the NYPD, Joe Kenny. He says that Luigi Mangione was born and raised in Maryland and has ties to San Francisco, California.

Kenny adds that Mangione's last known address was in Honolulu, Hawaii.

"He has no prior arrest history in New York," Kenny says.

We're now hearing that the suspect was carrying a US passport, a mask that was "consistent" with the one worn by the wanted individual, a firearm and a suppressor.

He was also carrying a fraudulent New Jersey ID that was used to check into the New York City hostel, we are told at the press conference.

Police say they have also recovered handwritten documents that they believe speak to the suspect's "motivation and mindset".

They add that NYPD detectives are en route to Pennsylvania to interview the suspect further.