TRENTON, N.J. (AP) — 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.

New Jersey Gov. Chris Christie addresses a gathering at a town hall-style meeting, Thursday, March 20, 2014, at St. Magdalen de Pazzi parish center in Flemington, N.J. (AP)

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.