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.

MICHAEL D. KELLEHER, who has written widely on the subject of violence, specializes in threat assessment, strategic management, and human resources management for organizations in the private and public sectors.DAVID VAN NUYS is Chair of the Psychology Department at Sonoma State University in Northern California. He serves on the board of directors of Division 32 (Humanistic Psychology) of the American Psychological Association. Van Nuys earned his doctorate in clinical psychology from the University of Michigan and has worked as a licensed psychotherapist in both New Hampshire and California. A frequent public speaker, he has also published in professional journals, popular magazines and was the author of a nationally syndicated newspaper column. In addition to his university teaching, Van Nuys is President of e-FocusGroups, a market research consulting firm.