NEW YORK (TNND) -- As the investigation continues, police officials have said that it is more than likely that the gunman who killed the CEO of UnitedHealthcare left New York City on a bus.
The gunman left his backpack in Central Park, but four days later, police still do not know the identity of the killer. The gunman wore the backpack during the shooting, but it was not found until Friday by investigators after a massive sweep through the area.
Police have not revealed what was in the backpack.
Joseph Kenny, Chief of Detectives, told reporters that investigators are looking into whether or not the gunman was an employee or a client of the largest U.S. health insurer.
The video of the gunman shows him riding a bike into Central Park and then taking a taxi to the Port Authority bus terminal. According to Kenny, he could've gone to New Jersey, Philadelphia, Boston, or Washington, D.C..
Kenny said that police have video of him entering the bus station, leading them to believe he left New York City after killing Brian Thompson.
On Friday, the FBI announced a $50,000 reward for information on the gunman to hopefully lead to his arrest and conviction.
The gunman left a trail of evidence throughout New York City, originally arriving on Nov. 24. Kenny said that the gunman went to New York City from a bus that originated in Atlanta.
It is believed that the gunman used fake identification and paid in cash when he checked into his hostel. Investigators have tested a water bottle and protein bar wrapper for the suspect's DNA.
The gunman's roommates at the hostel said that he did not speak to them and nothing of value was found in the room by police.
The only photos of the suspected gunman's face are in the lobby of the hostel, where his mask is off.
On each of the three bullets, the words "delay," "deny" and "depose" were written after being previously reported by a law enforcement official that it was "deny," "defend" and "depose". The phrase is commonly used by lawyers in the health insurance industry to describe rejecting claims.
Thompson had worked for UnitedHealthcare since 2004 and had been the CEO for the past three years. He was in New York City to attend UnitedHealth Group Inc.'s annual investors meeting.
Since the shooting, many health insurance companies have taken down photos of their executives from their websites.
Anyone with information about the suspect's identity or location is asked to contact the NYPD at 1(800)577-TIPS.