State Auditor David Yost is investigating three charter school sponsors following a string of closures. The sponsors are Aloysius Orphanage in Cincinnati; the North Central Ohio Educational Service Center in Marion and Tiffin; and the Warren County Educational Service Center. Yost is also auditing the Ohio Department of Education and reviewing its charter process. 29 percent of Ohio charter schools have closed since 1997. Before charters can open, they must have a sponsor to act as a check on decision-making.