Mad magazine.
The first three letters in this particular cipher are A, E and N. Some believe that these letters, symbolising the initials of Alfred E. Neuman, reinforce the
Mad theory.
The face of Alfred E. Neuman is framed by attendees at the DC booth during the first day of Comic-Con International at the San Diego Convention Center in San Diego.(AP)
Some of the the Zodiac killer s victims, San Francisco taxi driver Paul Stine, Cecilia Shepard, 22, a college student stabbed to death and Bryan Hartnell, 20, who survived a stabbing.(Nine Archives)
The Z 32 cipher instructed readers to use it in combination with a map.(History.com)