At this point, years and conspiracy theories later, wouldn’t the more important question to ask FIRST be, “Why did Jack Ruby kill Oswald?” Working from the last act back to the first might give more answers at this time. Was Ruby just acting out of anger and grief? Was he trying to be the hero who offed the baddest guy around? Answer Ruby’s actions and the answer to the rest of the story becomes clear.
Let me think. Why did Ruby kill Oswald?
Could it be to shut him up?
Possibly.
No.
The first question any detective would ask about a murder victim is this:
How did the victim die?