No, the prosecution has to prove guilt beyond a reasonable doubt. Once that’s done, then it takes a little more than an uncritical presentation or re-presentation of the defense side to prove innocence. You have to come up with some kind of hard evidence, like DNA or something like that.
His sister saying something sixty five years after the fact isn’t that kind of hard evidence. Unsworn testimony of someone the defense hired and which is not subject to cross-examination isn’t really it either.
Regards,
Shodan