Mangione is next due to appear in court on December 23.

Pennsylvania Governor Josh Shapiro said murder charges in New York state would follow, telling a media briefing “we do not kill people in cold blood to resolve policy differences or express a viewpoint”.

Police have not confirmed reports the words “delay” and “deny” – language used by insurers to reject claims – were written on casings found at the scene, hinting at a possible political motive for the crime.

According to a New York Times report citing friends of Mangione, the suspect lived with serious back pain and underwent surgery for the condition last year.

A photo on what appeared to be one of his social media accounts included an X-ray of an apparently injured spine.

Mangione was apprehended by officers after a tip from staff at an Altoona McDonald’s branch, where he was found wearing a mask and a beanie while using a laptop, and gave officers a fake ID, charging documents show.

They then searched him and found what police called a “ghost gun” capable of firing 9mm rounds and equipped with a suppressor that could have been made on a 3D printer.

When officers asked if he had been to New York recently, Mangione “became quiet and started to shake”, according to the criminal complaint.

One of the fake IDs found was that used to check in to a Manhattan hostel ahead of the attack, discovered alongside a document that spoke to Mangione’s “motivation and mindset”, New York police said.

Mangione was born and raised in Maryland, studied at the Ivy League University of Pennsylvania and had been living in Hawaii prior to the killing.

Mangione’s LinkedIn profile showed he worked as a data engineer at TrueCar, a California-based online auto marketplace that said he left their employment in 2023.

His family released a joint statement late on Monday local time saying they are “shocked and devastated by Luigi’s arrest”.

Fled by bike

In last Wednesday’s shooting, the gunman walked up behind Brian Thompson, a senior executive at UnitedHealthcare – one of the country’s largest medical insurers – and shot him dead in front of bystanders.

The attack was captured by a surveillance camera and the footage seen by millions around the world, as interest in the manhunt and mystery over the killer’s motives built to a frenzy.

Thompson, 50, was attending an investor conference in the Midtown business district.

Detectives said the suspect fled the crime scene on foot before riding a bike to Central Park, and later boarding a bus from a terminal in the north of the city connecting New York to surrounding states and beyond.

Video footage shows Thompson on the sidewalk outside the New York Hilton Midtown when a man in a hooded top, his lower face covered, approaches from behind and fires several shots at the father-of-two, who crumples to the ground.

An image released of the suspect was obtained from the youth hostel where the gunman apparently stayed before the hit, with media reporting he had lowered his mask to flirt with a receptionist.

The highly profitable US medical insurance system is the source of deep frustration and anger among many Americans, due to its steep costs and limited coverage, and Thompson’s death was greeted with an absence of sympathy by some.

A Facebook post mourning his loss, shared by UnitedHealth Group, racked up more than 71,000 laugh emojis within two days before the counter was disabled.

Mangione must now be extradited from Pennsylvania to New York to face murder charges, police said.