The question first came to my attention in the book, “This is the Zodiac Speaking” (Westport, CT: Praeger Publisher, 2002) by Michael Kelleher and Dr. David Van Nuys. In that book, clinical psychologist, Dr. Van Nuys, to my mind made a very persuasive argument and actually came out with a formal diagnosis that, in his professional opinion, the killer known as Zodiac was very likely suffering from Dissociative Identity Disorder.
Personally, I am generally very skeptical about the role psychology plays in criminal investigations, especially since it is a fairly common “defense ruse” for many serial killers. (Think Hillside Strangler killer, Kenneth Bianchi’s faking his “multiple personalities” and blaming the murders on one of his other personas.)
However, after a careful review of Dr. Van Nuys point by point diagnosis of Zodiac and taking into account my own ten-year investigation into the “Jekyll and Hyde” personality of my father, Dr. George Hill Hodel, I found myself seriously questioning my own skepticism.
In fact, I found Dr. Van Nuys detailed listing of the many “symptoms” and early-life behavioral causes so convincing and so much in line with what I knew about my own father’s life and demonstrated psychology, that I included Dr. Van Nuys probable diagnosis in the closing chapters of my own book. For those interested in more detail, I would highly recommend you read from, “This Is the Zodiac Speaking,” Dr. Van Nuys summary and ten-page clinical diagnosis found in his chapter: The Mind of A Killer: Reflections of David Van Nuys
Question #2- Can DID influence and change the handwriting of its author and or “alters”?
During my research I came across a fascinating article by sociologists, Dr. Eli Somer and Ron Yishai entitled, Handwriting Examination: Can It Help In Establishing Authenticity In Dissociative Identity Disorder? Below is their introduction to the paper along with a link to the full article:
Eli Somer, Ph.D., is on the faculty of the School of Social Work at the University of Haifa, and Director of the Israel Institute for Treatment and Prevention of Stress, both in Haifa, Israel . Ron Yishai, M .A ., is the Director of Yishai Forensic Graphology, in Haifa, Israel.
An earlier version of this paper was presented at the Fifth Spring Conference of the ISSD, Amsterdam, May, 1995.
Questions with regard to the genuineness of amnesia and DID in forensic settings have been of considerable past concern in trials of accused criminals claiming amnesia, accused perpetrators of incest and psychotherapists accused of negligently implanting memories or creating DID symptoms . This study has used document examination methods to investigate 30 different manuscripts suspected to have been mailed by three alters of a DID patient . In the present single case study we have found that despite the striking differences between the three handwritings identified, single authorship of the documents could be established. We have also shown that these handwritings could not have been a result of conscious disguise, and we were thus able to determine the authenticity of the phenomenon. Forensic implications of these findings are discussed.
Were the below handwriting samples written by three separate authors or just one? (See full article)
HW Samples from the Somer/Yishai research on DID and HW analysis