An N.Y.P.D. Manhunt Caught a Subway Shooter. This Time, It’s Different.

A shocking early morning act of violence, a frantic New York Police Department search for a suspect and a gunman seemingly in the wind: The year was 2022, and the man the police had fanned out to find was Frank R. James, who had set off smoke grenades inside a crowded subway car in Brooklyn and opened fire.

Now, more than two years later, another manhunt has gripped the city. But unlike Mr. James, who was apprehended the day after his rampage, the man who assassinated the chief executive of a health insurance company just before dawn on Wednesday in Midtown Manhattan has not been caught or even identified after more than four days.

The two most recent fugitive searches in New York City have involved gunmen who made seemingly improbable escapes in a city teeming with surveillance cameras and people. But despite some similarities between the cases and the investigative tactics being used to try to solve them, the search for the man who killed Brian Thompson, the chief executive of UnitedHealthcare, has proved far more challenging.

The suspect’s ability to evade capture appears to be tied to his methodical planning, including wearing a mask and a hood during nearly all of his time in New York City and paying with cash everywhere, along with using a fake driver’s license.

And unlike Mr. James, who did essentially nothing to conceal himself after slipping away amid the chaotic aftermath of the shooting that wounded 10 people, the suspect in Mr. Thompson’s killing fled quickly into Central Park, away from the surveillance cameras that blanket much of Manhattan. He also appears to have left the state long before the police could possibly have begun to track his movements.

“I don’t think I’ve seen this level of operational preplanning in any crime, never mind in a murder,” said Kenneth E. Corey, a former chief of department in the New York Police Department.