Federal prosecutors dropped their lawsuit Tuesday against former Arizona Corporation Commissioner Gary Pierce and three other people listed in an ongoing bribery case.

The move came less than a month after the initial trial ended with a mistrial.

Among the three others caught up in the case was utility lobbyist Jim Norton, who had been accused of hiring Pierce's wife in a vote-buying scheme allegedly to influence the commissioner's decision on utility rates. However, the defense said prosecutors had difficulty proving federal bribery laws were actually violated.

With the case closed, Norton expects to return to lobbying.

"Mr. Norton is glad to have this matter behind him so that he can get back to assisting his clients," said his attorney Ivan Mathew.

The U.S. Attorney's Office declined to comment and Pierce's attorney prefers to speak only after the judge has actually signed the order.