NEWARK, N.J. (AP) -- A longtime associate of Gov. Chris Christie, whose tenure as chairman of the Port Authority of New York and New Jersey has come under scrutiny from federal prosecutors, is retiring from one of New Jersey's most powerful law firms.

David Samson, former chairman of the Port Authority of New York and New Jersey (Andrew Burton/Getty Images)

The firm Wolff & Samson announced Tuesday that founding partner David Samson will retire this month. He is 75.

It also announced that Jeff Chiesa, a former U.S. senator and state attorney general, has been promoted to a new leadership role and the firm is being renamed Chiesa Shahinian & Giantomasi PC.

"After heading the firm and working relentlessly for 43 years, David Samson has been planning his ultimate retirement and leadership succession for some time," firm spokesman Mark Weiss said in a statement announcing the changes. "David's departure is a bittersweet occasion for the firm-wide family. David's colleagues and many friends will certainly miss him."

Samson said in a statement provided by spokeswoman Karen Kessler: "For personal, professional and health reasons I have made the decision to retire. After my five decades practicing law, it was time for new leaders to transition the Firm for the future."

Samson, a former state attorney general who was chairman of Christie's transition team before being picked as Port Authority chairman, resigned in the wake of the George Washington Bridge scandal and questions that he may have used the post to help the law firm's clients.

The firm, for instance, was working for New Jersey Transit when the port awarded it a $1-a-year lease for a park-and-ride lot that had previously cost $900,000 annually.

Federal authorities have subpoenaed records looking into whether Samson received preferential treatment from United Airlines over flights between Newark and Columbia, South Carolina, where he has a vacation home. A direct flight between Newark and Columbia began while Samson was chairman and ended days after he resigned last year.

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