"I will periodically send my assassins to kill random conspiracy nuts in suspicious-looking ways. There is little danger that they will find out about my plans and no one would have believed them anyway, but the heroes will be convinced that they were killed for what they knew and will get so wrapped up in trying to foil my diabolical plan to give all trees epilepsy that my real plans will go unchallenged. Plus it gives my assassins something to do."
No false pattern can be created to cover a crime without bearing upon it some trace of its creator. It is better, then, to seek in events some pattern that already exists and then adjust your actions to it.
"Many take it for granted that if there was an assassination conspiracy, Jack Ruby must have been involved. In fact, many people believe there was a conspiracy precisely because of Ruby's murder of Lee Harvey Oswald, which had the effect — intentional or otherwise — of silencing the accused assassin.
"But whether there was a conspiracy or not, there is no reason to assume that Ruby must have been involved. In fact, logic tells us that no conspiracy could profit by silencing Oswald in such a public fashion: What's the point of eliminating one suspect while simultaneously handing the police another?"