N.J. Gov. Chris Christie has hired a law firm as federal prosecutors investigate whether any law was broken when one of his aides ordered an apparent politically motivated traffic jam. (Reuters)

The administration of New Jersey Gov. Chris Christie (R) has hired outside legal counsel to help it deal with a U.S. attorney inquiry into its role in crafting a politically motivated traffic jam, according to a person with knowledge of the situation.

Christie's office is bringing in Gibson, Dunn & Crutcher LLP. Leading the team will be former assistant U.S. attorney Randy Mastro, who co-chairs the law firm's litigation group.

"Their presence will bring an outside, third-party perspective to the situation, and they will be a valuable asset as we move forward," Christie's office said in a statement. "This Administration is committed to ensuring that what happened here never happens again. That’s what the people of New Jersey deserve."

A member of Christie's staff was recently implicated in the plot to create the traffic jam. Christie has said that aide, now-former deputy chief of staff Bridget Anne Kelly, lied to him and that he knew nothing about the scheme. Christie has left open the possibility that other staff members were involved in bridge-gate, but has said he wasn't aware if they were.

At the same time, federal auditors are launching a separate inquiry into the Christie administration’s use of federal disaster recovery funds for an ad campaign.