New photos of suspect's face released as police race to find gunman who killed UnitedHealthcare CEO

NEW YORK -- Police appear to be closing in on an identity of the man suspected of gunning down UnitedHealthcare CEO Brian Thompson in Midtown Manhattan, sources told ABC News on Thursday.

NYPD released new photos of the suspect's face without a mask on Thursday morning as the urgent manhunt continues.

Police have also sought a search warrant for a hostel in New York City where they believe the suspect may have been staying, sources said.

It appears the suspect shared a room with two other men, according to police sources.

Detectives are currently canvassing other hostels and locations on the Upper West Side and beyond, showing the suspect's picture as they work to identify him.

The masked gunman shot Thompson several times at close range on Wednesday morning outside a Hilton Hotel where he was attending a conference.

The "brazen, targeted attack" was "premeditated," NYPD Commissioner Jessica Tisch said. The motive remains unknown, police said.

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Detectives believe the gunman is not a professional killer, sources said. Bullet casings found at the scene had the words "deny," "defend" and "depose" written on them, police sources said.

It furthers their working motive that the suspect held grudge against the insurance company.

Thompson, 50, was in New York City for the UnitedHealthcare investors conference, which was scheduled to start at 8 a.m. His schedule was widely known, police sources said.

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The suspect -- who was caught on surveillance cameras before, during and immediately after the shooting -- had been lying in wait near the hotel.

Thompson was shot at about 6:40 a.m. After the shooting, the shooter fled on foot into an alley, where a phone believed to be linked to the suspect was later recovered, police sources said.

The suspect then fled on a bike and he was last seen riding into Central Park at 6:48 a.m., police said.

The shooter was caught on surveillance video at 5 a.m. the morning of the shooting outside Frederick Douglass Houses, a public housing project on the Upper West Side, sources told ABC News. That footage showed the suspect carrying what appeared to be an e-bike battery.

Police have recovered a water bottle and candy wrapper from the scene of the shooting which they believe are linked to the gunman. Fingerprint and DNA tests on the items are ongoing, law enforcement sources told ABC News.

Thompson's wife, Paulette Thompson, said in a statement that she was "shattered" by the "senseless killing."

"Brian was an incredibly loving, generous, talented man who truly lived life to the fullest and touched so many lives," she said. "Most importantly, Brian was an incredibly loving father to our two sons and will be greatly missed."

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Police urge the public to call Crime Stoppers at 1-800-577-TIPS with any information.

ABC News' Mark Crudele and Josh Margolin contributed to this report.