Federal investigators are looking into a former New Jersey prosecutor's allegation in a lawsuit he was fired because he complained about the dropping of an indictment involving a donor to Republican Gov. Chris Christie.

Bennett Barlyn says he had a more than hour-long conversation with a Department of Justice criminal investigator Wednesday. He says he provided details of the lawsuit and evidence to back up his claims.

The former Hunterdon County assistant prosecutor says the investigator asked him about an allegation former county undersheriff Michael Russo told a reporter Christie would "have this whole thing thrown out" after he was accused of misconduct and indicted in 2010.

Russo has denied making the statement. Christie has denied involvement.

A spokesman for New Jersey U.S. Attorney Paul Fishman declined to comment Thursday.