Jack Ruby

Assassanation
Jack Ruby was a night club owner who shot and killed Lee Harvey Oswald in the Dallas Police Station on live television. He shot Oswald while he was being carried by police in the abdomen at close range. Oswald died a couple hours later. He was sentenced to death at first, but a 2nd trial was in the works, he died in prison of pulmonary before the trial could start,

Motive
Like Oswald, Ruby's motive is unknown. Most belive he was trying to keep Oswald quiet, and that JFK's assassanation is all one big conspiracy.