ALTOONA, Pennsylvania, Dec 10 (Reuters) - Investigators

on Tuesday were mapping the movements of a 26-year-old man

charged with gunning down UnitedHealth ( UNH ) executive Brian Thompson

on the streets of Manhattan last week, after a sprawling

five-day manhunt concluded with his arrest at a fast food

restaurant in Pennsylvania.

Authorities have said they are also examining whether the

suspect, Luigi Mangione, was helped by an accomplice either

before or after the brazen shooting, which offered few immediate

clues to the gunman's identity.

Mangione was spotted at a McDonald's in Altoona,

Pennsylvania, on Monday by an employee who thought he looked

like the gunman in surveillance images released by police. A

gun, clothing and fake identifications found in his possession

all closely match those used by the shooter, police said.

He faces gun and forgery charges in Pennsylvania and was

arraigned in Altoona on Monday. Later that evening, prosecutors

in New York filed murder and gun charges and are expected to

seek Mangione's extradition in the coming days.

While the gunman's motive remains unclear, police have said

Thompson, the CEO of one of the nation's largest health

insurers, was deliberately targeted.

Mangione suffered from chronic back pain that limited his

daily life, according to several news accounts. His profile on X

shows a background image of an x-ray with what appears to be

screws and plates inserted in a lower back.

From January through June 2022, Mangione lived at the

Surfbreak co-living community, similar to an adult dormitory,

where he led a book club and surfed, hiked and rock-climbed,

according to the Hawaiian online news site Civil Beat and other

media.

The founder of the group, R.J. Martin, said Mangione's pain

lingered for years, caused by misaligned vertebrae that would

pinch Mangione's spinal cord, and he left for the mainland at

some point for surgery.

But he went "radio silent" in June or July, Martin told

Civil Beat.

At one point, Mangione suggested the group's book club read

the manifesto of Ted Kaczynski - the Unabomber - as a joke,

Martin said.

GHOST GUN

Mangione, an Ivy League graduate who was also the

valedictorian of a private all-boys school in Maryland, had a

loaded ghost gun - a firearm assembled from parts, making it

untraceable - and a silencer, officials said on Monday. Both the

weapon and his clothing closely resembled those used by the

gunman.

He also had a large sum of cash and multiple fake

identifications, including a fraudulent New Jersey ID that

matched the one used by the gunman to check into a Manhattan

hostel days before the shooting, according to authorities.

Police found a handwritten document that offers insight into

his motivation, officials said. The writing included the phrase,

"These parasites had it coming," the New York Times reported,

citing a law enforcement official.

Mangione's family released a statement saying they knew only

what had been reported in the media.

"Our family is shocked and devastated by Luigi's arrest,"

the family said in a statement posted to the X account of

Maryland lawmaker Nino Mangione. "We offer our prayers to the

family of Brian Thompson and we ask people to pray for all

involved."

BRAZEN ESCAPE

The gunman managed to elude capture for days after the

attack last Wednesday outside the Hilton hotel in midtown

Manhattan.

After lying in wait for Thompson, the masked suspect shot

him in the back before fleeing on foot, riding a bicycle into

Central Park and eventually making his way to a bus station in

northern Manhattan, where police believe he boarded a bus and

left the city.

The words "deny," "defend" and "depose" were carved into

shell casings found at the scene, several news outlets have

reported. The words evoke the title of a 2010 book critical of

the insurance industry, "Delay, Deny, Defend: Why Insurance

Companies Don't Pay Claims and What You Can Do About It."

Thompson's murder unleashed a wave of frustration from

Americans struggling to afford medical care and those who have

been denied claims or care.

Thompson, a father of two, had been CEO of UnitedHealth

Group's ( UNH ) 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.