Ever watch the History Channel late at night, Fistful?
They show programs delving into unsolved mysteries like Tunguska, where a conglomeration of "experts" theorize anything from a black hole passing through the Earth, to an asteroid impact, to anti-matter colliding with the Earth, etc. Then the show ends without anything being described as "definitive".
There was a BBC program a decade or so ago that focused on Alert 747/Vela Incident. I have a grainy copy of it on VHS somewhere. It ends with the narrator asking, "Was it a nuclear detonation or not? We don't know..." Duh.