Two words: double jeopardy.
They could find a videotape of Simpson stabbing Nicole and it wouldn’t be good for anything just like this knife. Not that the knife could be used for anything either even if there wasn’t double jeopardy attached. The word of someone “working on the estate” who gave it to an “off duty cop” doesn’t even come close to forming any kind of chain of custody.
OJ the Affirmative Action butcher.