The New Jersey assemblyman leading an investigation into the closure of access lanes to the George Washington Bridge in September said Tuesday that he had subpoenaed the appointee of Gov. Christie who allegedly ordered the controversial move.

David Wildstein, a high school friend of Christie's, resigned in early December as director of interstate capital projects for the Port Authority of New York and New Jersey following suggestions that the decision to close the lanes was punitive and politically motivated.

"This will be a thorough and complete investigation focusing on how this abuse of power and threat to public safety came about," Assemblyman John S. Wisniewski (D., Middlesex), chairman of the Transportation, Public Works and Independent Authorities Committee, said Tuesday.

The subpoena requires Wildstein to appear at a hearing scheduled for Jan. 9 in Trenton.

Wildstein's attorney, Alan Zegas, said he would discuss the subpoena with his client after New Year's Day.

Christie's top deputy at the authority, former Republican State Sen. Bill Baroni, testified voluntarily before a legislative panel that the lanes were closed as part of a traffic study. He also has resigned.

The authority's executive director, Patrick Foye, an appointee of New York Gov. Andrew Cuomo, testified before the Assembly panel in December that he knew of no such study.

Port Authority workers and officials have testified that Wildstein told bridge managers not to inform local officials in the small borough of Fort Lee, or higher ranking members in the Port Authority, about plans to shut down the lanes there.

The George Washington Bridge is the busiest bridge in the country. The closure caused traffic congestion for four days in September.

Some New Jersey Democrats have accused Christie's appointees of shutting down the lanes for political retribution against the Democratic mayor of Fort Lee because he did not endorse Christie, a Republican, for reelection. About 60 elected Democrats endorsed Christie, who secured a second term with a 22-point victory in November.

National Democrats have seized on the controversy as Christie considers running for president in 2016.

Wisniewski said his committee had received more than 900 pages of documents he requested via subpoena from Wildstein. The committee also has subpoenaed documents from five other Port Authority officials.

U.S. Sen. Jay Rockefeller (D., W. Va.) has called for a federal investigation of the closure.