Police have arrested a person of interest in connection with last week’s brazen murder of UnitedHealthcare CEO Brian Thompson, after a tip-off from a McDonald’s employee.

The 26-year-old suspect was eating at the fast food outlet in Altoona, Pennsylvania, and was reported by a staffer who recognised his similarity to police photos.

Authorities on Tuesday morning (AEDT) said Luigi Mangione, born in Maryland, was apprehended at McDonald’s.

He was found in possession of a gun, silencer and false identification cards similar to those used by the gunman.

He was also carrying a three-page, handwritten document that appeared to outline his feelings of “ill will” towards corporate America, NYPD Chief of Detectives Joseph Kenny said.

New York City Police Commissioner Jessica Tisch said the scrawled ramblings spoke to “both his motivation and his mindset”.

Mangione’s multiple fraudulent identifications included a fake New Jersey ID that matched the one used by the gunman to check into a Manhattan hostel days before the shooting.

Police said the gun he was carrying was likely a “ghost gun” made with a 3D printer and capable of firing a nine-millimetre round.

Mangione has been arrested on firearms charges by Altoona police. New York detectives were on their way to Pennsylvania to question him, Tisch said.

Luigi Mangione was arrested in Pennsylvania on Tuesday (AEDT). Photo: Facebook

Police said Mangione, who went to an Ivy League college in Pennsylvania, had no criminal record. His name was not on a list of suspects being worked on by police.

Brian Thompson, 50, was gunned down outside a Manhattan hotel early last Wednesday morning (local time) by a masked man who appeared to wait for his arrival before shooting the executive from behind.

The suspect ran from the scene and then rode a bike into Central Park.

Surveillance video captured him exiting the park and taking a taxi to a bus station in northern Manhattan. Police then believe he got on a bus out of the city.

Photos of the suspect helped lead to an arrest. Photo: NYPD

Thompson, a father of two, had been CEO of UnitedHealth Group’s insurance unit since April 2021, part of a 20-year career with the company.

He had been in New York to attend the company’s annual investor conference.

-with AAP