There are no signatures or other distinguishing marks on a ballot. This is a secret ballot as it is supposed to be. A signature audit can only check ballot envelopes against ballot applications or Signatures on record with the clerk's office. This will indicate a number of illegal ballots which can then lead to a determination whether there is sufficient evidence to throw out the election and re-vote in the case of local elections or go to the state representatives to determine how the electors would be apportioned.