“Zodiac continued to communicate with authorities throughout 1970 via letters and greeting cards to the press. After that, the Zodiac remained silent for nearly three years until he sent the Chronicle a letter praising The Exorcist as “the best satirical comedy” that he had ever seen. Even though the Zodiac sent many letters and cryptograms to various newspapers which were eventually decoded, there were some that no one could ever crack (Voigt, 2011).
Even with hundreds of people working on the case; there are many aspects that remain a mystery to this day. FBI handwriting analysts, forensic scientists and cryptanalysts all aided the local police departments in the investigations, yet no one could unsolve the nature of the murders or identify the Zodiac (FBI, 2007)”.