Ohio Rev. Code Ann. § 3309.29

To the extent to which it is used in determining the liability of any fund created by section 3309.60 of the Revised Code, the school employees retirement board shall verify the statement required by section 3309.28 of the Revised Code by the best evidence it can obtain. If official records are not available as to the length of service, compensation, or other information required, the board may use its discretion as to the evidence to be accepted.