A witness at the Pennsylvania McDonald's where Luigi Mangione was arrested said customers had remarked on the 26-year-old's resemblance to the suspect in the killing of a health insurance CEO last week.

Larry - who did not give his last name to media - said he believed one friend was joking around when he commented on it.

"I thought he was kidding. You know what I mean?" he told BBC News outside the fast-food restaurant.

Mr Mangione was charged on Monday night with murder over last week's fatal shooting of UnitedHealthcare CEO Brian Thompson in New York City.

Larry said he had gone to the McDonald's in the town of Altoona for a coffee with a group of "five or six" friends before attending church.

He said his friends noticed Mr Mangione in the restaurant, when he ordered and took a seat in the back.

One of his friends later told him he had noticed similarities between what the young man was wearing and what was worn by the suspect in the widely distributed images released by New York City police during their six-day hunt for the killer.

"I said to Mike this morning: 'When you said that, were you serious?' He said: 'Yeah, I was serious.'"

A restaurant employee also told him she had spotted the likeness. She took particular note of his "eyes and his eyebrows" while taking his order.

"It was like she got in her mind: 'Oh, my God, it's a guy from New York,'" Larry said on Tuesday.

Mr Mangione was detained by police at 09:58 local time (14:58 GMT) after being recognised by a customer at the fast-food outlet, who flagged their concern to an employee who then called local police.

Officers found him sitting in the restaurant wearing a blue mask and looking at a laptop. They said they recognised him as the suspect after he removed the mask.

When asked whether he had been to New York recently, he "became quiet and started to shake", according to an affidavit.

He was found in possession of a gun and a handwritten document that expressed "ill will" towards corporate America and a false ID, according to police.

Mr Mangione initially appeared in a Pennsylvania court on Monday charged with possession of an unlicensed firearm and other charges.

In New York, he faces second degree murder charges as well as charges for possession of a false ID and weapons possession charges.

Mr Thompson, 50, was shot and killed last Wednesday morning outside the Hilton hotel in Midtown Manhattan where the medical insurance giant he led was holding an investors' meeting.

The reaction to his killing exposed a deep-seated anger against the trillion-dollar industry, and on Tuesday, Altoona police told its officers to be on alert after receiving multiple emails and calls, including death threats from the public.

The McDonald's also received a flood of negative reviews online.

Police said that they appreciated remarks made on Monday night by Pennsylvania Governor Josh Shapiro, who criticised those who "have looked to celebrate instead of condemning this killer".

"He is no hero," Shapiro said.

Larry, who left the restaurant before the arrest, said he personally thought the young man who went to sit in the back corner after placing his order was an employee.

"They'll go back there on break and they'll take a rest, you know, maybe take a little sleep or something," he said.

Asked for his thoughts on one of the most wanted suspects in the US being arrested at his local fast-food restaurant, Larry said he was "a little bit surprised".

"But I'm not really surprised, you know?," he added.

"I mean, the way the world is right now, it's pretty crazy."