Chairman of NY-NJ Port Authority resigns amid scandal over lane closures near bridge

In this photo provided by ABC News, ABC News’ Diane Sawyer speaks exclusively to New Jersey Governor Chris Christie at his home in Mendham, N.J., Thursday, March 27, 2014. The Governor insisted that he “did nothing to create the environment” that prompted some of his former top aides to cause a traffic nightmare at the George Washington Bridge last fall. Portions of the interview aired on World News with Diane Sawyer and will also air on Nightline. Good Morning America Also plans to air some of the interview on Friday, March 28. (AP Photo, ABC, Ida Mae Astute) NO BOOK PUBLISHING WITHOUT PRIOR APPROVAL,; NO ARCHIVE; NO RESALE. (The Associated Press)

Attorney Randy Mastro speaks during a news conference Thursday, March 27, 2014, in New York. Mastro, with the law firm hired by New Jersey Gov. Chris Christie, said Thursday that the governor was not involved in a plot to create gridlock near a major bridge as part of a political retribution scheme. (AP Photo/The Record of Bergen County, Kevin R. Wexler, Pool) (The Associated Press)

TRENTON, N.J. – The chairman of the Port Authority of New York and New Jersey has resigned amid continuing questions about lane closures near the George Washington Bridge and whether he has used his position to boost his law firm.

New Jersey Gov. Chris Christie announced David Samson's resignation Friday. Samson is a former state attorney general.

Christie appointed him to run the board of the bistate agency that runs several New York City-area transportation facilities, including airports and bridges and tunnels.

People close to Christie engineered four days of gridlock in September. It was intended — for reasons that remain unclear — as retaliation against a mayor.