An acquaintance originally from the Chicago area, told me about coming home from college for Xmas that year. Ran into an old HS buddy (19 years old) who told him he had voted 18 times in the November election. Apparently he was paid so much per vote ... said it was easy money. Multiply that by several hundred people doing the same thing and you understand why there were voter irregularities in the Chicago area.
Multiply that by Bobby Kennedy's refusal to back off the Mob after Sam "Momo" Giancana's gargoyles made his brother president, and maybe you'll understand why two Kennedys got their brains blown out.
That's one theory, anyway. (There are also the Khrushchev and Castro theories.)