A person of interest wanted for questioning in the deadly shooting of UnitedHealthcare CEO Brian Thompson is believed to have left New York City, police said Friday. Meanwhile, investigators found in Central Park what’s believed to be the suspected gunman’s backpack, law enforcement officials told CBS News.

The officials told CBS News it’s not clear what the backpack contained. The New York Police Department said the backpack was being analyzed to determine if it belonged to the suspect, who is believed to have disposed of his backpack in Central Park as he was fleeing Wednesday’s shooting in midtown Manhattan.

Police have not named a suspect in the investigation, but investigators are looking for a person of interest who’s wanted for questioning in the case. The person of interest may have boarded a bus at a Manhattan bus terminal bound for Atlanta, a person familiar with the matter told CBS News. Joseph Kenny, the NYPD’s chief of detectives, told reporters Friday that investigators don’t know what bus the man may have taken.

“We have him in a taxicab, and the taxicab takes him up to 178th Street and Broadway, which as we know is a Port Authority bus center,” Kenny told CNN. “Those buses are interstate buses. That’s why we believe he may have left New York City.”

The Atlanta Police Department said that they were contacted by the New York Police Department and will be providing assistance as needed. Investigators were following leads in New York, New Jersey and Connecticut.

Days before the shooting, the person of interest took a bus that had originated in Atlanta to New York City, a person briefed on the investigation confirmed to CBS News on Thursday. It is unclear when the person of interest got on the bus, whether it was in Atlanta, or on another stop along the way.

When the person was in New York City, he used a fake ID with a fake name to check in to Hostelling International New York City, a hostel on Amsterdam Avenue, in the Upper West Side neighborhood of Manhattan, according to a law enforcement official with knowledge of the investigation. The official said police believe the name on the ID was made up and does not belong to anyone else.

The NYPD shared two images Thursday showing the person at the hostel. They did not say when the photos were taken.

The photos were taken with his mask pulled down as he talked to a woman at the front desk. New York police interviewed the woman, who told officers she asked to “see his pretty smile,” a high-ranking source told CBS News New York.

“They were having a flirtatious moment and he pulls it down and he gives a big smile and that one informal moment between two human beings remains at this moment the most significant clue to date in this whole case,” said John Miller, former NYPD deputy commissioner for intelligence and counterterrorism.

Kenny told reporters that the person of interest was seen on security video arriving at the Port Authority Bus Terminal in midtown Manhattan between 10 p.m. and 11 p.m. on Nov. 24.

Police were able to identify him with surveillance video of him walking through the terminal, police sources with direct knowledge of the investigation previously told CBS News. That video was used to trace him to a Greyhound bus.

From the Port Authority, he took a cab to the vicinity of the Hilton Midtown hotel — near which the fatal shooting of Thompson occurred on Dec. 4 — and was there for about 30 minutes. He then took a cab to the hostel, Kenny said. He briefly checked out of the hostel on Nov. 29, Kenny said, but then checked back in on Nov. 30. 

Bus riders who pay cash for a ticket aren’t required to show a valid ID. Port Authority police is working with Greyhound to determine if the person of interest provided ID at any point, and they are investigating at which point he purchased the ticket between Atlanta and New York.