Jack Ruby was the man who assassinated the assassin. He should also be credited as the father of the modern conspiracy industry, because had he turned up at Dallas Police Headquarters 20 seconds later, or had any number of other happenstances intervened, he would never have got to Oswald, the latter would have been put on trial, and the whole non-mystery would have died with him.
The way things played out has been called serendipity. Obviously this was not so serendipitous for Oswald, but realistically he had nothing to look forward to anyway.
The documentary makers speak to many people including Ruby's brother, one of the dancers from his club, and Warren Commission member Burt Griffin who said they were actively looking for a conspiracy to undermine the FBI. In another documentary on the same subject, Griffin said if they had indeed found this (mythical) conspiracy, he would have been the Senator for Ohio rather than John Glenn. We also hear part of Ruby's last interview, recorded covertly as he lay dying from cancer while awaiting a retrial on the most spurious of pretexts.
We hear too from the conspiratards, who really have nothing to offer in spite of later conclusions of mob involvement. The real culprit (apart from Ruby) was America's open justice, which is frankly too open in many respects. In the UK, after his arrest, Oswald would have been shielded from the media and public, and contempt of court laws would have restricted any reporting. Jack Ruby is best summed up by the Deep Purple song: "...no method in my madness, no craft, no guile". In short, whatever else he may have been, including mad, Jack Ruby was first and foremost his own man.
