The two lawmakers co-leading the investigation announced the subpoena in a statement issued Wednesday.
"This subpoena is a necessary step in the committee's bipartisan investigation into the lane closings and apparent abuse of government power and threat to public safety," Assemblyman John Wisniewski (D) and Senate Majority Leader Loretta Weinberg (D) said. "Mr. O'Dowd is in a unique position to provide insight into what happened under his watch as chief of staff to the governor. We look forward to his cooperation and testimony."
The short time frame between the announcement of the subpoena and the scheduled testimony is a break with the investigative committee's past behavior. Until now, the lawmakers have issued subpoenas for testimony well ahead of the dates when individuals have actually appeared to answer questions.
O’Dowd has been Christie's chief of staff since 2012, and perviously served as the governor's deputy chief counsel. His time working with Christie stretches back to the U.S. Attorney's Office in New Jersey. Last year, Christie announced his intention to nominate O'Dowd to become state attorney general, but the nomination was put on hold, reportedly as a result of the investigation into the September lane closure, which caused a multi-day traffic jam in Fort Lee, N.J.
A spokesman for Christie did not immediately respond to a request for comment.