Philip Kwon, the Port Authority of New York and New Jersey's deputy general counsel, spent parts of four to five days helping Bill Baroni prepare for testimony before a New Jersey legislative committee Nov. 25, the official told the Wall Street Journal.
Baroni told the state Assembly Transportation Committee in November the lanes were closed to determine the fairness of having three local-access lanes for Fort Lee, N.J.
The George Washington Bridge, the world's busiest for motor vehicles, crosses over the Hudson River between Fort Lee and New York City.
The lane closures became a political crisis for Christie last month after emails were released that showed his aides and allies purposefully caused massive traffic backups in Fort Lee over five days, starting Sept. 9.
Baroni was the authority's deputy executive director at the time of his testimony, which was not under oath. He was also the authority's top executive appointed by Christie.
Baroni resigned three weeks after testifying, following sworn testimony by authority Executive Director Patrick Foye and other authority officials.
They said there was no study, the closures were unlawful and Baroni and David Wildstein, who ordered them, had violated protocols and sought to hide their plans from officials.
Baroni and Wildstein tried to keep word of the closures, and of Fort Lee officials' fury, from becoming public, emails released by an Assembly committee indicated.
An authority spokesman told the Journal Kwon's preparations of Baroni didn't take five days. He also defended Kwon's work.
"Meeting with a witness prior to testimony is a routine function of any lawyer and any attempt to assign ulterior motives to this general practice is unwarranted," the spokesman said.
State Sen. Loretta Weinberg, co-chairwoman of a legislative special committee investigating the scandal, said she would try to get an an explanation of Baroni's preparations.
"What concerns me is why the Port Authority or any member of the Port Authority staff, if the allegation is true, would have to spend four or five days preparing somebody who told this story that is obviously incorrect," she told the Journal.
Kwon didn't respond to a Journal request for comment.
Baroni's attorney declined to comment.
Kwon got his Port Authority job in July 2012, after Democratic lawmakers rejected his nomination by Christie to the state Supreme Court, partly over concerns about his family's finances.
Separately, a Christie aide who was subpoenaed in the growing scandal has resigned, the aide said through her lawyer.
Christina Renna, former director of departmental relations, submitted her resignation Friday, her attorney said Sunday.
Documents released by the Assembly indicate she knew a Fort Lee official was alleging "government retribution" during the lane closures.
Renna said in a statement her decision to leave was something she was "considering since shortly after the election." She said she continued to "respect and admire" Christie.
Her attorney, Henry Klingeman, did not say if Renna planned to respond as required Monday to her subpoena from state lawmakers investigating the scandal, Politico reported.
Christie spokesman Colin Reed declined to comment on Renna's departure.