Police divers were seen searching a pond in Central Park, where the killer fled after the shooting.

Officers have scoured the park for days for any clues and found his backpack there on Friday. They didn’t immediately reveal what, if anything, it contained but said it would be tested and analysed.

On Sunday morning, police declined to comment on the backpack’s contents or the results of the search in the pond, saying no updates were planned. Investigators have urged patience, saying the process of logging evidence that stands up in court isn’t as quick as it appears on TV.

Hundreds of detectives are combing through video recordings and social media, vetting tips from the public and interviewing people who might have information, including Thompson’s family and coworkers and the shooter’s randomly assigned roommates at the Manhattan hostel where he stayed.

Investigators caught a break when they came across security camera images of an unguarded moment at the hostel where he briefly showed his face.

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Retracing the gunman’s steps using surveillance video, police say it appears he left the city by bus soon after the shooting outside the New York Hilton Midtown. He was seen on video at an uptown bus station about 45 minutes later, NYPD’s Kenny said.

With the high-profile search expanding across state lines, the FBI announced on Friday it was offering a $US50,000 ($78,000) reward for information leading to an arrest and conviction, adding to a reward of up to $US10,000 that the NYPD has offered. Police say they believe the suspect acted alone.

Police previously distributed the images to news outlets and on social media but said they haven’t been able to ID him using facial recognition technology – possibly because of the angle of the images or limitations on how the NYPD is allowed to use that technology, NYPD’s Kenny said.

AP, Reuters

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