Special prosecutor Donald Caldwell announced the indictment in a statement Monday. He did not identify the staffer who worked on Scott Taylor's campaign in Virginia's coastal 2nd Congressional District.
A ballot-fraud scandal clouded much of Taylor's campaign last summer. Staffers were accused of forging voter signatures to place a third-party "spoiler candidate" on November's ballot.
A judge ultimately removed the candidate, Shaun Brown, from the race. The judge also said there was evidence of fraud by Taylor's campaign staffers. Democrat Elaine Luria ultimately won the election.
Caldwell said the investigation into election fraud is ongoing. He said some people have not cooperated with his investigation.