UnitedHealthcare CEO shooting suspect, unmasked in new photos, believed to have left message on bullet casings

The suspected gunman wanted in the broad daylight slaying of UnitedHealthcare CEO Brian Thompson is seen smiling in new surveillance images released by the New York City Police Department on Thursday. 

The unknown man's face is shown for the first time in the two new images the NYPD released as the manhunt continues for a second day. 

"With these new photos, if indeed they are the shooter, it is now only a matter of time," Fox News crime analysis contributor Paul Mauro told Fox News Digital. "Facial recognition and other technologies have come a long way, and my understanding is that the police have been making progress on other fronts in this case. It is truer than ever that you can’t get away with murder these days. The detectives will get whoever is behind this, and soon."

The NYPD was spotted searching a hostel on the Upper West Side of Manhattan, and a Brazilian tourist staying there told Fox News he believes Thompson's assassin was in the room next door to him. 

The vice president of Hostelling International USA, which runs "HI New York City Hostel," however, did not confirm the suspect stayed there. 

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"We are fully cooperating with the NYPD and, as this is an active investigation, can not comment at this time," Hostelling International USA Vice President Danielle Brumfitt Norris said in a statement. 

The floor design of the hostel appears to match that same black and white checkered pattern seen in the wanted photos shared by the NYPD. 

New evidence also suggests that the suspect who killed Thompson on Wednesday may have left a message behind on the bullet casings at the scene.

Police sources told the New York Post that the words "deny," "depose" and "defend" were written on the live rounds and casings left behind by the assassin after the shooting.

Evidence also shows that each bullet and casing had just one word written on it leading them to believe he may have been trying to leave a message, sources said. The words on the ammunition may have been a reference to strategies insurance companies use to try to avoid paying claims, the Associated Press reported.

In a shocking video obtained by Fox News Digital, Thompson is seen walking down a New York City sidewalk when a masked man wearing a black hooded jacket and a backpack walks up behind him and raises a handgun.

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PHOTOS OF SUSPECT INSIDE STARBUCKS:

The culprit fired off several shots. At one point, the gun appeared to jam. The assailant then appeared to smack the gun on the side while walking toward the victim, who was attempting to get away.

Following the shooting, the suspect walked between two vehicles, got onto a bike, then disappeared into Central Park, the NYPD said.

It was previously reported that the suspect used a Citi Bike – which can be tracked – but the NYPD has clarified that the incident did not involve that type of bike.

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Investigators hope accompanying evidence left behind will help identify him, including a cellphone discovered in an alleyway near the hotel where the shooting occurred as well as a cup in a trash can at a nearby Starbucks. 

UnitedHealth Group released a statement expressing their condolences and surprise at the day's events.

"We are deeply saddened and shocked at the passing of our dear friend and colleague Brian Thompson, the CEO of UnitedHealthcare. Brian was a highly respected colleague and friend to all who worked with him. We are working closely with the New York Police Department and ask for your patience and understanding during this difficult time. Our hearts go out to Brian’s family and all who were close to him."

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Anyone with information is encouraged to contact Crime Stoppers at 1-800-577-TIPS, or for Spanish, 1-888-57-PISTA. Tips can also be submitted on the Crime Stoppers website by visiting crimestoppers.nypdonline.com.

Fox News' Tamara Gitt and Greg Wehner contributed to this report.