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The helicopter lifted off in a damp fog and raced down the East River. But within minutes, the pilot was trying to return to the heliport he had just left.

The pilot, an experienced flier named Timothy McCormack, told the heliport he could not find his way.

“McCormack then stated that he did not know where he was,” a law enforcement official said on Tuesday.

That was Mr. McCormack’s last communication before he crashed and died on the roof of a 51-story office tower in the middle of Manhattan on Monday afternoon, the official said.