Episode 80 - The End of Innocence - How did Jack Ruby get so close to Oswald to shoot him?

This week we focus our attention on Jack Ruby. What was Ruby up to the morning of Sunday, November 24 - the morning he shot Lee Harvey Oswald in the basement of the Dallas Police Department? How did Ruby get himself into a position to make that shot? And is there reason to believe that Ruby’s relationship with police officers allowed him to get access to Oswald in the basement?