Prosecutors of the task force ultimately forced Mr. Chang and six others to plead guilty to campaign-financing violations, and all seven agreed to cooperate with the authorities.
The office of the United States attorney in Manhattan, which took over the investigation from Justice Department prosecutors in February, has largely put aside earlier questions of possible campaign-financing violations by Mr. Torricelli, a Democrat, in the 1996 Senate race.
He faces six counts of conspiracy and campaign finance violations.
His lawyer has denied any campaign finance violations.
Federal prosecutors are examining the party for possible campaign finance violations.
Multiple Wisconsin prosecutors investigated Walker's campaign committee for what they suspected were campaign finance violations.
Mr. Don has pleaded guilty to campaign finance violations and is cooperating with prosecutors.
Her testimony led to his conviction last November for campaign finance violations.
He has pleaded not guilty to six counts related to campaign finance violations.
