The man suspected of gunning down UnitedHealthcare CEO Brian Thompson outside a Midtown Manhattan hotel took a taxi to the Port Authority bus facility at 178th Street and boarded a bus out of New York City following the shooting, according to police.
The unidentified man remains at large in the wake of Wednesday's attack, which was described by police as "brazen, targeted" and "premeditated."
The FBI is assisting in a nationwide manhunt for the suspect, according to law enforcement sources. The bus the suspect is believed to have boarded out of the city made six or seven stops, and investigators have followed leads in multiple states, the sources said.
Police still do not have a name of the suspect, the sources said.
UnitedHealthcare CEO shooting timeline: How police tracked killer's movements
In another development in the investigation, police officers have recovered what is suspected to be the backpack carried by the suspected shooter, a source familiar with the case tells ABC News.
The bag was discovered Friday evening in Central Park, where the NYPD deployed an army of officers and drones to conduct a grid search, the source said.
The suspect is seen in footage wearing a backpack prior to the shooting but does not appear to have it on in another video of him on a bike 15 minutes after the shooting.
The suspected killer of Thompson entered New York City by bus November 24, when a surveillance camera at Port Authority Bus Terminal caught his arrival at 9 p.m., law enforcement sources told ABC News.
The inbound bus originated in Atlanta but it was not immediately clear where the suspected boarded. However, sources said he was spotted on board in Washington D.C., so he boarded there or somewhere between DC and Atlanta.
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Investigators believe they were able to score DNA samples from several pieces of evidence discovered at or near the murder scene, law enforcement sources told ABC News on Friday.
The samples are currently at the Office of the Chief Medical Examiner to be run through databases for possible match, the sources said. That process could take a couple of days.
Thompson, 50, was killed around 6:45 a.m. Wednesday outside the New York Hilton. He was in town from Minnesota for his company's investor conference.
THE INVESTIGATION
NYPD's Crime Stoppers bureau has fielded hundreds of tips flooding in from around the region and the country.
Unconfirmed reports of sightings on Friday have sent law enforcement responding in cities like Atlanta and states like Texas. On Thursday, an Amtrak train was stopped in Connecticut and an LIRR train was stopped by MTA police.
Detectives in the Crime Stoppers bureau worked through the night fielding calls and tips at 800-577-TIPS and online. Police are encouraging everyone to come forward with information, even with the smallest bit of information.
The 10-day period between the suspect's arrival and the murder is the focus of investigative efforts.
Detectives are also running down any possible lead. One theory brought detectives investigating a sale of a gun that closely resembles the one believed used in the shooting to a Connecticut gun dealer. But the guy's purchaser has been identified and is not a suspect.
Police have collected a trove of surveillance video of the suspect all over the city - in the subway, in cabs, in a McDonald's and in a Starbucks. Each place he paid with cash and he made sure to keep his mask on, which indicate to detectives he knew he was coming to the city to commit the murder.
Police were able to extract a fingerprint off the water bottle the suspect acquired at a Starbucks, but the fingerprint is smudged. It's unclear to what extent the fingerprint will be helpful in the search for a killer.
Meanwhile, a Greyhound spokesperson said they are cooperating with the NYPD investigation, but said they "cannot provide further comment at this time."
Police sources also told ABC News that the suspect checked into the HI New York City Hostel located at 104th Street and Amsterdam on the Upper West Side on Nov. 30. It's believed he arrived in the city prior to that date and detectives continue their video canvass to gain a fuller picture of his movements.
The new developments come after the NYPD released new photos of the suspect without a mask Thursday, apparently from when he stayed at the hostel.
A law enforcement source told Eyewitness News that the suspect's unmasked smile came as he flirted with the front desk clerk who checked him into the hostel, and encouraged him to drop the mask so she could see his smile. The suspect obliged, pulling his mask down long enough for the surveillance camera to capture his face.
New York City Mayor Eric Adams said on Friday that the NYPD is "on the pathway to bring this person to justice," saying detectives are making significant progress, citing the un-masked photo.
"This person was fully masked and we used good old fashioned police work to come up with the picture that you have," Adams said.
The photo represents an important image for investigators, and police are confident someone will recognize him.
It appears the suspect shared a room on the fourth floor with two other men, and checked into the 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.
A POSSIBLE MOTIVE?
Police say Thompson's schedule for the investor conference was widely known.
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.
It's not clear if any words were exchanged prior to the shooting.
The gunman, described as 6'1" with a tall, thin build, ran through the midblock Ziegfeld Alleyway and eventually jumped on a bike and rode away into Central Park.
"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 a 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.
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Detectives still do not have the suspect's name and they have his cellphone but have not accessed it.
Police are still searching for the e-bike he used that was last seen on West 85th Street.
Detectives are interested in every moment of the 10 days the suspect spent in New York City, and will be canvassing the Upper West Side, Midtown, and possibly other neighborhoods for surveillance until there is none left.
A $10,000 reward is being offered for information.
The Associated Press and ABC News contributed to this report.