New York police believe the man who fatally shot him CEO of UnitedHealth has left town, Police Commissioner Jessica Tice said Friday, as the manhunt for the gunman passed the critical 48-hour mark.

Brian Thompson, 50, was shot in the back on Wednesday in what police believe was a targeted attack. The authorities made public many photos of the suspect – who fled the scene, got on an electric bike and disappeared into Central Park – and asked for help in locating him.

Authorities found a backpack in Central Park Friday that they believe belongs to the suspect, CNN reported, citing unnamed police sources. The discarded backpack, likely filled with evidence, was not located in the initial search but was later found inside the 843-acre park, CNN reported.

Tice said in an interview with CNN that authorities believe the gunman has fled New York after new video surfaced showing him arriving at a bus station.

New York Police Department Chief Joseph Kenney, in the same interview, said the video showed the suspect taking a taxi that took him to a Port Authority bus station near the George Washington Bridge in Upper Manhattan.

“These are interstate buses. That’s why we think he may have left New York, Kenny said.

Police have not identified the suspect, at least not publicly. They believe he arrived in New York 10 days before the shooting on a Greyhound bus from Atlanta and checked into a youth hostel in Manhattan using a fake New Jersey ID, multiple media outlets reported. Reuters has not independently verified this account.

Police offered a $10,000 reward for information leading to an arrest and conviction.

Police also revealed that the suspect was spotted at a nearby Starbucks minutes before the shooting. Investigators have so far not identified a motive for the murder, although police noted that the assailant fled without taking any of the victim’s belongings.