MIDTOWN (WABC) -- Police in New York City appear to be closing in on an identity of the suspect wanted in the fatal shooting of UnitedHealthcare CEO Brian Thompson, sources told ABC News.

The NYPD released new photos of the suspect without a mask Thursday, apparently from when he stayed at the HI New York City Hostel on the Upper West Side. It appears the suspect shared a room with two other men, according to police sources.

The suspected shooter checked into the Upper West Side hostel using a New Jersey license that isn't his, police sources told ABC News.

Detectives ran the name and found it did not resemble any known photos of the suspect or other evidence amassed so far, the sources said.

Separately, surveillance footage reviewed by police shows someone who appears to be the suspect exiting the subway prior to the shooting at the 57th Street station, just blocks from the shooting scene. The suspect was spotted on surveillance footage about 5 a.m. Wednesday outside the hostel holding what appeared to be an e-bike battery.

Police are working to determine if the suspect prepositioned the bike and took the subway to the shooting scene.

"Deny," "defend" and "depose" were written on the live rounds and shell casings discovered at the scene of Wednesday morning's shooting - which detectives interpret as a possible message from the suspect.

It furthers their working motive that the suspect held grudge against the insurance company. They are checking every dispute or contested denial of service brought against the company, as well as running down every threat made against the UnitedHealthcare CEO.

Thompson, 50, from Minnesota, was shot around 6:45 a.m. outside the New York Hilton on Sixth Avenue between 53rd and 54th streets in what police say was a "brazen targeted attack."

The CEO was in New York City for an investor conference at the Hilton and his schedule was widely known.

NYPD detectives tracing sales of the kind of gun used to kill the UnitedHealthcare CEO arrived at a shop in Connecticut on Thursday that sold the same type of gun, according to police sources.

Police believe the shooter used a B &T Station Six, known in Britain as a Welrod pistol.

The gun does not have a silencer but rather a long barrel that enables the 9mm to fire a nearly silent shot.

It requires manually cycling ammunition from the magazine, which is consistent with what is seen in the video of the shooting. The weapon is not easily attainable so investigators have been running down all recent purchases.

The actual gun used in the shooting of Thompson has not been recovered so this is one investigative lead authorities are following.

The shooter appears to have known which door Thompson was going to enter and was spotted on video at least five minutes prior to the shooting loitering around the hotel. Thompson was approached from behind and shot several times at point blank range at the doorway on West 54th Street, including several rounds in the back and once in the right calf.

At one point the gun appeared to jam. When the suspect cleared the jam, he resumed shooting.

It's not clear if any words were exchanged prior to the shooting.

The gunman is described as 6'1" with a tall, thin build, and was wearing a black jacket, black hat, black ski mask, and black backpack. He ran through the midblock Ziegfeld Alleyway and eventually jumped on a bike and rode away into Central Park.

A new video released on Thursday shows the alleged suspect biking out of Central Park, on West 85th Street, after the shooting.

Investigators also recovered surveillance images from a Starbucks one block north, where the suspect visited a few minutes before the shooting, and a cellphone was found along the escape route.

While a suspect has not yet been identified, police believe they will recover good forensic evidence from a water bottle and two power bar wrappers that were discarded at the same Starbucks where police also obtained the surveillance video of the suspect. They say the unspent bullet rounds and the cell phone, which they now have a search warrant to examine, will help in their investigation as well.

A $10,000 reward is being offered for information.

ABC News contributed to this report.

READ MORE: What we know about the gunman in the murder of Brian Thompson, UnitedHealthcare CEO

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