...except how does one defend himself after 40 years?
And that is why we have statutes of limitations. And jury trials. And the presumption of innocence, and the requirement to prove guilt beyond a reasonable doubt.
Good Lord ... if all we have is "Smith says Jones committed unspeakable acts" forty years ago and "Jones denies any such thing occurred" ...
I'm going with Jones. An accusation is not evidence. Prove it.