The investigation in New York comes on top of a similar probe by feds in New Jersey, who are investigating the September closings of access lanes to the George Washington Bridge.
The New York probe was not supposed to be looking at the lane closures. A source has told ABC News that the New York probe is likely to be folded into the New Jersey investigation because of the common ground between the two: the Port Authority is in the middle of both, as is Samson and other New Jersey appointees to the bi-state agency.
Jim Margolin, a spokesman for the US attorney in Manhattan, said he would neither confirm nor deny, citing Justice Department rules.
A spokeswoman for Samson issued a comment on behalf of Samson's attorney, former Homeland Security Secretary Michael Chertoff: "We are not commenting on the progress of investigations."
Feds are looking into potential conflicts between Samson's private business interests and his actions as chairman of the Port Authority which runs the region's airports, Hudson River crossings and the World Trade Center.
Samson is the senior partner of one of New Jersey's biggest law firms, Wolff & Samson.
Samson is not paid for his chairmanship role. He was a New Jersey attorney general under then-Gov. Jim McGreevey and ran Christie's transition in 2009-2010. His firm was counsel to Christie's campaigns.
Information from ABC News.