UnitedHealthcare CEO killer 'made a lot of mistakes,' former NYPD commissioner points out

It's only a 'matter of time' before an arrest is made in the fatal shooting of UnitedHealthcare CEO, said Ray Kelly

The suspect behind the UnitedHealthcare CEO’s death seemingly made "a lot of mistakes," according to New York City’s longest-serving police commissioner, but there’s one clue that makes it a "matter of time" before he’s in custody.

"The circulation of his picture, I haven't seen anything like that in quite a while and probably was in every newspaper in America, and probably every TV station put that picture up. So I think it's just a matter of time," Ray Kelly said on "Mornings with Maria" Monday.

"He made a lot of mistakes," he continued. "Obviously, this is one of them, the picture where he smiles at the desk clerk. And that is a pretty good picture."

The manhunt for the suspect who murdered UnitedHealthcare CEO Brian Thompson has entered its sixth day, after Thompson was fatally shot early Wednesday morning outside of the Hilton hotel in Midtown Manhattan. On Monday afternoon, a source with knowledge of the investigation into the murder of UnitedHealthcare CEO Brian Thompson told Fox News that a person fitting the suspect's description has been taken into custody at a McDonald's in Altoona, Pa.

USERS MOCK UNITEDHEALTHCARE C.E.O.'S MURDER

After opening fire, the alleged gunman fled via e-bike into the streets of the Big Apple and prompted a large-scale manhunt. Police recovered a backpack linked to the murder that contained a jacket and Monopoly money and have not revealed a motive, though bullet casings at the scene were found with the words "deny," "depose" and "defend" written on them.

Wanted poster for UnitedHealthcare gunman

A wanted poster is set up for an NYPD press conference regarding a homicide that authorities believe was a targeted attack on UnitedHealthcare CEO Brian Thompson. (Getty Images)

Multiple images of the suspect have been released to the public, with one surveillance image showing his face was obtained while he was flirting with a hostel staff member prior to the shooting, reports say.

"Facial recognition is very, very effective these days. Some police departments don't use it unless they're looking at people who have already been arrested. So it's [a] sort of self-imposed limitation, but facial recognition is effective, and I would hope that it's being used in this case," Kelly explained.

"I think it's just a matter of time, and I think good work has been done so far."

Police believe the gunman eventually went to an Upper Manhattan bus terminal and boarded a public transportation vehicle.

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"I think it’s pretty easy to miss him… It's logical that he would do that. And we don't know: Did he go to an airport?" Kelly posited. "Did he take the bus to an airport? Did he get [to] the airport?"

"They're pretty certain that this individual left the city. So the focus is going to shift," the former police commissioner added. "There are investigators who are in Atlanta, the FBI is assisting the NYPD, and these things take time. It's understandable that it does take time."

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Fox News staff contributed to this report.