Ohio Rev. Code Ann. § 2953.21
(A)
(1)
(a) A person in any of the following categories may file a petition in the court that imposed sentence, stating the grounds for relief relied upon, and asking the court to vacate or set aside the judgment or sentence or to grant other appropriate relief:
(c) As used in division (A)(1)(a) of this section:
(e) At any time in conjunction with the filing of a petition for postconviction relief under division (A) of this section by a person who has been sentenced to death, or with the litigation of a petition so filed, the court, for good cause shown, may authorize the petitioner in seeking the postconviction relief and the prosecuting attorney of the county served by the court in defending the proceeding, to take depositions and to issue subpoenas and subpoenas duces tecum in accordance with divisions (A)(1)(e), (A)(1)(f), and (C) of this section, and to any other form of discovery as in a civil action that the court in its discretion permits. The court may limit the extent of discovery under this division. In addition to discovery that is relevant to the claim and was available under Criminal Rule 16 through conclusion of the original criminal trial, the court, for good cause shown, may authorize the petitioner or prosecuting attorney to take depositions and issue subpoenas and subpoenas duces tecum in either of the following circumstances:
(viii) That the parties simultaneously file specified documents or information enclosed in sealed envelopes to be opened as directed by the court.
(2)
(3)
(G) A petitioner who files a petition under division (A)(1)(a)(i), (ii), (iii), or (iv) of this section may amend the petition as follows:
(J)