You'll have to take that up with the state legislature -- in this case, the Ohio state legislature. I don't make the rules, but historically murder has been considered too heinous to allow anyone to be officially "off" because a certain number of years has passed.
It is heinous all right, so, either you find the murderer and punish for the crime within - say, 10 years - or, if ten years wasn't enough, you forget the whole thing instead of falling for the "ritualistic killing" and other imaginary BS as is this very case.