Ruby died of cancer, didn't he? . . .
I just took a look:
https://www.history.com/this-day-in-history/january-3/jack-ruby-dies-before-second-trial
On January 3, 1967, Jack Ruby, the Dallas nightclub owner who killed the alleged assassin of President John F. Kennedy, dies of a massive blood clot in a Dallas hospital. The Texas Court of Appeals had recently overturned his death sentence for the murder of Lee Harvey Oswald and was scheduled to grant him a new trial.
On November 24, 1963, two days after Kennedy’s assassination, Lee Harvey Oswald was brought to the basement of the Dallas police headquarters on his way to a more secure county jail. A crowd of police and press with live television cameras rolling gathered to witness his departure. As Oswald came into the room, Jack Ruby emerged from the crowd and fatally wounded him with a single shot from a concealed .38 revolver. Ruby, who was immediately detained, claimed he was distraught over the president’s assassination. Some called him a hero, but he was nonetheless charged with first-degree murder.