Well, you're not clear here.<quoted text>
The witnesses are dead.
So, if your grandfather was accused of rape, but vindicated by a witness, and the case closed, can you reopen the case because the witness is now dead? Can someone now accuse your grandfather of rape?
I rest my case.
If the grandfather was charged with rape, tried, and acquitted, he could not be charged again with the same crime. It's called double jeopardy and it's a no-no.
If the case was "closed" by the prosecutor, before a trial, the grandfather could again be charged with the crime, as long as the statute of limitations has not expired.