By Hilary Russ
(Reuters) - New Jersey Governor Chris Christie on Friday said his transportation commissioner Jamie Fox would step down by the end of the month to return to the private sector after only a year in the position.
Fox was previously a lobbyist with airline company United Continental Holdings Inc. before Christie tapped him to be transportation czar in September 2014.
Federal authorities are conducting a criminal probe into the previous relationship between United, during Fox's tenure there, and David Samson, former chairman of the Port Authority of New York and New Jersey.
Federal investigators are probing flights that United added between Newark, New Jersey, and Columbia, South Carolina, near Samson's vacation home.
Samson, appointed by Christie, resigned in March 2014 amid additional probes into business dealings his law firm had with the Port Authority while he was Chairman.
United's former Chief Executive Jeff Smisek and two other senior executives stepped down in September amid the probe and an internal investigation into the so-called "chairman's flight."
Christie's office said in a statement that Fox will "make his anticipated transition back to the private sector," with the current deputy chief Joseph Bertoni to take over as Acting Commissioner.
Christie, a Republican candidate for the presidential nomination in 2016, nominated Fox, a long-time Democrat, for the position in September 2014. The state Senate confirmed him later that month.
Fox has been in New Jersey politics and transportation for decades, previously serving as transportation commissioner in 2002 and deputy executive director of the Port Authority.
He was also in top staff positions with two former Democratic New Jersey Governors, James McGreevey and James Florio.
Fox did not return a call seeking comment on Friday. Christie's office did not reply to a request for additional details.
(Reporting by Hilary Russ; Additional reporting by Jeffrey Dastin; Editing by David Gregorio)