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UPDATE, 1:30 p.m. ET: According to WNBC-TV, two senior law enforcement officials said a fake New Jersey ID found on the male being questioned displays the name “Marc Rosario.” The station added that three sources familiar with the matter said the suspected gunman checked into a New York City hostel using a fake New Jersey ID displaying the name “Marc Rosario.”

Original story below

Police on Monday were questioning a male in Pennsylvania in connection with the fatal shooting of UnitedHealthcare CEO Brian Thompson last week in Manhattan, two sources familiar with the matter told WNBC-TV.

Sources told the station that customers at a McDonald’s in Altoona thought the male looked suspicious and called police; arriving officers noticed a fake ID and took him in for questioning. Altoona is about two hours east of Pittsburgh. Sources added to WNBC that officers at the station discovered the male was in possession of a gun similar to the one used in Thompson’s killing along with a silencer.

Police told the station they believe the suspect acted alone and used a 9mm gun resembling guns farmers use to put down animals without a loud noise.

The station said the male had a fake New Jersey ID, adding that the suspected gunman allegedly used a fake New Jersey ID when he checked into a Manhattan hostel in November.

WNBC added that the male may have taken a bus to get out of New York, and sources told the station that investigators are looking into whether he recently exited a bus from Philadelphia.

Sources also told the station that New York City Police detectives are headed to Pennsylvania to question the male and assist investigators.

More from WNBC:

The development comes as a private funeral is set to be held Monday for Thompson, the 50-year-old executive gunned down at point-blank range as he headed to a midtown hotel for an investors’ conference last Wednesday, according to a source familiar with the plans.

Five days after the shooting — by a man captured on surveillance cameras across Manhattan — the killer remains on the loose. The nation’s largest police department is after him, along with the FBI, as the trail takes detectives to Atlanta. Despite obtaining a clear image of his face among other evidence, authorities have yet to identify him.

Late Saturday, police released two additional photos of the suspected shooter that appeared to be from a camera mounted inside a taxi. The first shows him outside the vehicle, and the second shows him looking through the partition between the back seat and the front of the cab. In both, his face is partially obscured by a blue, medical-style mask.

The new photos came after authorities recovered a gray bag possibly belonging to the suspect in Central Park. The bag was taken, unopened, for forensic processing before investigators were to review its contents. Sources later said the bag contained a jacket and Monopoly money, but no gun. DNA testing is ongoing.

Police told the station surveillance video was used to retrace the gunman’s movements, and it appears he left New York City by bus soon after the shooting. NYPD Chief of Detectives Joseph Kenny said he was seen on video at an uptown bus station about 45 minutes after the fatal shooting, WNBC said.

Police told the station they believe the suspect acted alone and used a 9mm gun resembling guns farmers use to put down animals without a loud noise.

Bullet casings recovered at the scene of Thompson’s killing outside a Manhattan Hilton — which the police called a “brazen” and “premeditated, preplanned targeted attack” — apparently were inscribed with words referring to health insurance claim denial tactics. NBC News reported that three live 9mm rounds and three discharged 9mm shell casings were found. Citing two law enforcement officials, the New York Times said police are investigating apparent messages on the casings, specifically words such as “delay” and “deny,” which may point to ways health insurance companies attempt to avoid paying patient claims.

The New York Post published a similar report, noting that sources said words such as “deny,” “depose,” and “defend” were engraved on live rounds and shell casings. The Post added that the words are similar to the main title of a 2010 book, “Delay, Deny, Defend: Why Insurance Companies Don’t Pay Claims and What You Can Do About It.” CBS News published a video report discussing the apparently engraved words.

Kenny told WNBC that the shooter knew UnitedHealthcare group was holding a conference at the hotel and what route Thompson might take to get to the hotel — and that it suggests the shooter could be a disgruntled employee or client.

According to the station, police said video indicates the gunman was in New York City for 10 days prior to the shooting, arriving at Manhattan’s main bus terminal on a Greyhound bus that originated in Atlanta. WNBC said it isn’t clear if the gunman got on the bus in Atlanta or in another stop along the way to New York City.

The station said that around 11 p.m. on the night he arrived in New York City, he took a taxi to the HI New York City Hostel — and that there he briefly pulled down a mask and smiled while speaking with an employee in the lobby, which gave investigators a look at his face.

You can view a video report here about police questioning the male in Altoona.

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