Fumo is accused of defrauding the Senate by having staffers do campaign work for himself and his political allies on Senate time. The powerful Democrat is on trial in federal court in Philadelphia.
But his lawyers say taxpayers weren't defrauded because staffers worked evenings and on weekends to make up for Senate time spent on unofficial business.
Spagna was testifying for the government Friday under a grant of immunity. She also told jurors how she did personal chores for Fumo during the workday.