CHICAGO (AP) — The chairman and CEO of United Airlines is stepping down in connection with an investigation into dealings with the agency that operates New York-area airports.

United Continental Holdings Inc. said Tuesday that Jeff Smisek and two other senior executives had resigned and railroad executive Oscar Munoz was named CEO and president.

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United disclosed earlier this year that the company and some of its executives had received subpoenas from a federal grand jury for information about dealings with the Port Authority of New York and New Jersey. United said it was conducting its own internal investigation.

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Former Port Authority chairman David Samson’s activities have been subject of document requests from the U.S. attorney’s office in New Jersey, including Samson’s votes on United Airlines projects at Newark Airport at the same time United was restarting flights from Newark to Columbia, South Carolina, near where Samson has a vacation home.

United began an about twice-weekly direct flight from Newark to Columbia that began after Samson became chairman and was canceled days after he resigned last year.

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