Federal prosecutors in Manhattan on Friday subpoenaed the Port Authority of New York and New Jersey for records related to potential conflicts of interest involving its chairman, David Samson, a prominent New Jersey lawyer and close political ally of Gov. Chris Christie, according to people briefed on the matter.

On Monday, the subpoena was withdrawn, apparently to clear the way for the investigation to be pursued by federal prosecutors in New Jersey, who had already been reviewing the politically charged closing of access lanes to the George Washington Bridge in September, according to two of those briefed on the matter.

The business dealings of Mr. Samson and his law firm, Wolff & Samson, have come under intense scrutiny as a result of the lane closings and the scandal that ensued, which are the subject of a separate inquiry by federal prosecutors in New Jersey, who are examining the roles of several current and former aides and allies of Mr. Christie.

It was not immediately clear why federal prosecutors in Manhattan, in the office of Preet Bharara, the United States attorney there, had issued the subpoena when their federal counterparts in New Jersey were conducting the bridge inquiry and the related investigation.