New video obtained by ABC News shows UnitedHealthcare CEO Brian Thompson's killer waiting for him moments before shooting Thompson outside a Midtown Manhattan hotel last week.

The video shows others pass by, and then, when the masked gunman sees Thompson, he runs across the street and opens fire.

The video, which has not previously been seen publicly, appears to support the police narrative that the shooter targeted Thompson in the Wednesday morning attack because he loitered while others wandered by.

Police haven't established a motive but said they haven't uncovered evidence that would show the killing had anything to do with Thompson's private life.

The unidentified suspect appeared to have planned his movements with precision, but law enforcement is "on the right track," New York City Mayor Eric Adams told New York ABC station WABC on Sunday.

"As I say, the net is closing and closing," Adams said. "This was an extremely challenging investigation. A fully masked person. The amount of detective work it took to put the pieces together -- we feel we're getting closer and closer."

The FBI is assisting the nationwide manhunt, according to law enforcement sources.

NYPD detectives arrived this weekend in Georgia. Investigators have said the suspect arrived in New York on Nov. 24 on a bus that originated Atlanta, although it's unclear if his travels began in Atlanta.

The masked gunman shot Thompson at point-blank range at 6:44 a.m. on Wednesday outside the New York Hilton Midtown, where Thompson's company was holding an investors conference. NYPD Commissioner Jessica Tisch described the attack as "brazen" and "targeted."

Right after the shooting, the suspect fled by bike through Central Park to the Upper West Side. He then took a taxi to the Port Authority bus facility at 178th Street and boarded a bus out of New York City, according to police.

NYPD officials released new images this weekend of the suspect in the back of a taxi, where he could be seen peering through the open slider in the partition between the seats. Another photo appeared to show the man walking by the window of a cab.

In New York on Sunday, members of the New York Police Department's dive team searched underwater in Central Park near the Bethesda Fountain.

Adams on Sunday declined to comment on specific evidence, saying only that "every piece is important." And he spoke generally about the ongoing underwater search.

"Everywhere is important. Everyplace is important," Adams said, adding a moment later, "It's dark down there, you know."

The suspect's backpack -- with a jacket and Monopoly money inside -- was found nearby in Central Park. Police have not yet recovered the distinctive gun used in the shooting.

"I don't want to do anything that's going to tip him off that we're on his trail, but we feel really good where we are," Adams said on Sunday. "Finding the knapsack, getting the cab photos, looking at some of the evidence that we have available to us, we feel really good where we are."

ABC News' Bill Hutchinson, Jon Haworth, Ivan Pereira and David Brennan contributed to this report.