Motions for new trial on account of newly discovered evidence shall be filed within one hundred twenty days after the day upon which the verdict was rendered, or the decision of the court where trial by jury has been waived. If it is made to appear by clear and convincing proof that the defendant was unavoidably prevented from the discovery of the evidence upon which he must rely, such motion shall be filed within seven days from an order of the court finding that he was unavoidably prevented from discovering the evidence within the one hundred twenty day period.
Ohio. Crim. R. 33