California was thrown into a paralysis of fear in 1969, horrified by the elusive Zodiac serial killer. The Zodiac became the most enigmatic and frustrating adversary ever encountered by the law enforcement community in the San Francisco Bay Area. Over 30 years later, the Zodiac killings remain unsolved. The authors analyze the Zodiac's crimes and supply psychological insight to his letters providing a glimpse into the mind of a mysterious murderer.